Ringing-RZ Code


Alternating Current (AC) sent out from the central office along the local loop to the subscriber. It's typically 70 to 90 volts at 17 Hz to 20 Hz. You can get a mild shock if you have your hands on a telephone circuit when ringing current comes along. The rest of the time, the lines are harmless.

Ringing Generator

A device in a phone system that generates the AC ringer voltage. Typically, this voltage is 90 to 115 (nominally 105) VAC at 30 Hertz.

Ringing Key

A key that sends a ringing current.

Ringing Signal

Any AC or DC signal transmitted over a line or trunk for the purpose of alerting someone or some thing at the distant end of an incoming call.

Ringing Tone

A low tone which is one second ON and three seconds OFF. It indicates that ringing current is being sent by the central office to the person receiving the call. Ringing tone is not produced by the calling party's central office ” but by the called party's central office. Thus, it is possible for you to hear ringing tone but for the person you are calling not to hear anything. As a general rule, if the person doesn't answer, call them a second time. Often, they'll say "The phone never rang." This will not be a lie, but simply a temporary glitch in their central office.

Ringing Transfer

A PBX feature which allows you to choose which bells in a group of phones will ring when a call is coming in for that group .

Ringing Voltage

In addition to talk battery, a Central Office provides ringing signaling. Ring Voltage is generally 70 to 90 volts at 17 Hz to 20 Hz. See also Ringing.


  1. Routing Information Protocol. RIP is based on distance-vector algorithms that measure the shortest path between two points on a network, based on the addresses of the originating and destination devices. The shortest path is determined by the number of "hops" between those points. Each router maintains a routing table, or routing database, of known addresses and routes; each router periodically broadcasts the contents of its table to neighboring routers in order that the entire network can maintain a synchronized database. See also Distance Vector Protocol.

  2. To record your CD or DVD's content to your PC's hard disk. You'll need to do this if you wish to transfer your CDs to an MP3 player ” either one containing a hard disk (e.g. Apple's iPod) or simply flash memory, such as some of the MP3 players made by Sony. Software on the PC which is used to "rip" CDs does not refer to the process as ripping. They refer to it as importing or recording.

Rip Cord

A cord placed directly under the jacket of a cable in order to facilitate stripping (removal) of the jacket.


Reseaux IP Europeens, a group formed to coordinate and promote TCP/IP based networks in Europe. RIPE is responsible for management and assignment of IP (Internet Protocol) addresses in Europe, just as are ARIN and APNIC in the regions of the Americas and Asia-Pacific, respectively. RIPE holds periodic conferences to coordinate technical issues (similar to the IF) as well as running a Network Control Center (NCC) to handle operational issues such as the administration of the European domain names and routing tables. RIPE is a collaborative organization with no formal membership (over 1,000 organizations participate); all activities are performed on a voluntary basis. See also APNIC, ARIN and IP.

RIPscrip Graphics Emulation

Supports RIPscrip Graphics Emulation. Popular on many bulletin board systems, RIPscrip Graphics Emulation allows users to view screens mixing text and graphics. On-screen buttons can be clicked to send commands to a remote system. Now effectively obsoleted by the World Wide Web.


Regional Internet Registries. A collective term for the three non-profit organizations (ARIN, RIPE NC, and APNIC) established to register and administer IP number allocations and assignments. See also ARIN, RIPE, and APNIC.


Reduced Instruction Set Computing. A microprocessor architecture that favors the speed at which individual instructions execute over the robustness of the instruction set. Computers based on RISC use an unusual high speed processing technology that uses a far simpler set of operating commands. These commands greatly speed a computer's performance, especially for calculation- intensive operations such as those performed by scientists and computer-aided design (CAD) and computer-aided manufacture (CAM) engineers . RISC is a design that achieves high performance by doing the most common computer operations very quickly. In contrast, the microprocessors used in most PCs are based on a design called CISC (Complex Instruction Set Computing). CISC does not execute instructions as quickly as RISC but it has more commands and accomplishes more with each command. Programs written for RISC are typically not compatible with those written for CISC processors. RISC is the prevailing technology for workstations today. The RISC semiconductor was an IBM baby, born in its Yorktown Heights, NY lab in 1974. But internal arguments over, and even whether the chip should be used kept IBM fiddling while Sun and other companies decisively powered ahead. IBM got its first good RISC product, the RS/6000, to market in 1990. The PowerPC architecture is one example of a RISC microprocessor design. See also CISC.


The conduit or path between floors of a building into which telephone and other utility cables are placed to bring service from one floor to another. Your risers should be twice the size you ever think you'll need in the next 30 years . It's expensive to build risers after the building is built. Very expensive.

Riser Cable

High strength cables intended for use in vertical shafts between floors in multi-story buildings . Such shafts are called riser shafts. (What else would they be called?)

Riser Closet

The closet where riser cable is terminated and cross connected to either horizontal distribution cable or other riser cable. The riser closet houses cross connect facilities, and may contain auxiliary power supplies for terminal equipment located at the user work location. See also Satellite Closet.

Riser Subsystem

The part of a premises distribution system that includes a main cable route and facilities for supporting the cable from an equipment room (often in the building) to the upper floors, or along the same floor, where it is terminated on a cross connect in a riser closet, at the network interface, or other distribution components of the campus subsystem. The subsystem can also extend out on a floor to connect a satellite closet or other satellite location.


A potential liability, caused by a threat.

Risk Assessment

The process of quantifying the potential impact on an organization from various security threats.

Risk Management

Process of identifying, controlling, and eliminating or minimizing uncertain events that might adversely affect system resources.


Remote Integrated Services Line Unit. One of the remoting arrangements that the Lucent 5ESS switch architecture permits . The RISLU terminates DSLs and connects to the switch DLTU via T-1.


Remote indoor Service Unit. A cable telephony term for a Remote Service Unit which interfaces the coax-based CATV system to the twisted pair inside wire and cable system in support of voice and high-speed Internet access, as well as cable TV. The RiSU is mounted indoors, and contains a battery backup, as well as an A/C (alternating current) transformer. See RSU for more detail.


Rate of Information Transfer. The amount of information that can be communicated from a sender to a receiver in a given length of time.


Registered Jacks. They're telephone and data plugs registered with the FCC. RJ-XX (where X is a number) are probably the most common plugs in the world. Here is a table of the most common registered jacks, courtesy the FCC. Following the table are descriptions of the most common RJ jacks .


RJ-11 is a six conductor modular jack that is typically wired for four conductors (i.e. four wires). The RJ-11 jack (also called plug) is the most common telephone jack in the world. The RJ-11 is typically used for connecting telephone instruments, modems and fax machines to a female RJ-11 jack on the wall or in the floor. That jack in turn is connected to twisted wire coming in from "the network" ” which might be a PBX or the local telephone company central office. In a home installation, the red and green pair would be used for carrying the phone conversation and the black and white might be used for carrying low voltage from a plugged-in power transformer to light buttons on the phone. In many offices, the tip and ring were used for the voice conversation and the black and white were used for signaling. Increasingly, these days more and more office phone systems use only one pair, i.e. the red and green conductors. A friend always the green conductor for TIP and the red for RING. In a touchtone phone, the green and red conductors are color specific. If you have them wired the wrong way, often you can't generate touchtones. Simple solution: Reverse the wiring.

See also RJ-22 and RJ-45.

RJ-12C and RJ-12W

These jacks are normally associated with one line of a key telephone system. They provide a bridged connection to the tip and ring of the telephone line and to key system A and A1 leads. The tip and ring conductors in the jack are connected ahead of the key telephone-system line circuit. The RJ-12C is surface- or flush- mounted for use with desk telephone sets while the RJ-12W is for wallmounted telephone sets. Typically, these arrangements are used when registered ancillary equipment must respond to central office or PBX ringing.

RJ-13C and RJ-13W

Jacks normally associated with one line of a key telephone system. They provide a bridged connection electrically behind the key-system line circuit to the tip and ring conductors and to the A and A1 leads. The RJ-13C is surface- or flush- mounted for use with desk tele-phone sets while RJ-13W is for wallmounted telephone sets. These arrangements are generally used when the registered ancillary equipment does not require central office or PBX ringing to function properly.


A jack that looks and is exactly like the standard RJ-11 that you see on every single line telephone. Whereas the RJ-11 defines one line ” with the two center, red and green, conductors being tip and ring, the RJ-14 defines two phone lines. One of the lines is the "normal" RJ-11 line ” the red and green conductors in the center. The second line is the second set of conductors ” black and yellow ” on the outside. The RJ-14C is surface- or flushmounted for use with desk telephone sets while the RJ-14W is for walmounted telephone sets.


The RJ-15C is a weatherproof jack arranged to provide single-line bridged connection to tip and ring. Jack RJ-15C can be arranged for surface- or flushmounting depending upon customer needs.


A providing a single-line bridged tip and ring and is associated with -9 dBm (per- missive) data arrangements that require mode indication for use with exclusion key telephone sets. The exclusion key telephone set requires a series jack, RJ-36X (described under 8-position jacks) as its normal means of connection.


A jack that provides a single-line bridged connection of tip and ring to special telephone sets or ancillary equipment (e.g., ECG machines) in hospital critical-care areas. Only registered equipment conforming to Article 517 of the 1978 National Electrical Code is permitted to connect to this jack arrangement. This jack differs from the RJ-11C in that tip and ring appear on pins 1 & 6 rather than 3 & 4.


A jack providing a bridged connection of single-line tip and ring with make-busy leads MB and MB1. When the registered equipment provides a contact closure between the MB and MB1 leads, a make-busy indication is transmitted to the network equipment busying out the line from further incoming calls. It's recommended that the busy indication (contact closure) be provided while the line is in the idle state to reduce the possibility of interfering with a call that is in the ringing or talking state. The RJ-18C is surface-or flush- mounted for use with desk telephone sets.


A jack normally associated with one line of a key telephone system. It provides a bridged connection of single-line tip and ring behind a key-system line circuit, with A and A1 lead control, and a direct connection for MB/MB1 make-busy leads. When the modem provides a contact closure between the MB and MB1 leads, a make-busy indication is transmitted to the network equipment busying out the line from further incoming calls. It's recommended that the busy indication (contact closure) be provided while the line is in the idle state in order to reduce the possibility of interfering with a call that is in the ringing or talking state. The RJ-19C is surface or flushmounted for use with desk telephone sets.


Same as an RJ-21X. See RJ-21X.


An Amphenol connector under a different name . Here's the explanation: Amphenol is a manufacturer of electrical and electronic connectors. They make many different models, many of which are compatible with products made by other companies. Their most famous connector is probably the 25-pair connector used on 1A2 key telephones and for connecting cables to many electronic key systems and PBXs. The telephone companies call the 25-pair Amphenol connector used as a demarcation point the RJ-21X. The RJ-21X connector is made by other companies including 3M, AMP and TRW. People in the phone business often call non-amphenol 25-pair connectors, amphenol connectors. The RJ- 21X is often used with Traffic-Data Recording Equipment and Multiple-Lien Communications Systems. The user must specify the connection sequence for each title appearing in the jack.


RJ-22 is a four position modular jack that is typically used for connecting telephone handsets to telephone instruments. It is always wired with four conductors (also called wires). It is different and slightly smaller than the more common RJ-11 which is typically used for connecting telephone instruments, modems and fax machines to a female RJ-11 jack on the wall or in the floor. That jack in turn is connected to twisted wire coming in from "the network" ” which might be a PBX or the local telephone company central office. See RJ-11 and RJ-45.


This jack is associated with a telephone company-provided key telephone system when connection to several lines is required. It provides bridged connections of up to 12 telephone lines and their associated A and A1 leads. The tip and ring conductors in the jack are wired ahead of the lien circuit in the key telephone system. This arrangement is used when the modem must respond to central office or PBX ringing.


This jack is normally associated with a telephone company-provided key telephone system when connection is required to several lines. It's wired to provide bridged connections of up to 12 key-system line circuits and associated A and A1 leads. It differs from and is preferred over the RJ-22X, in that tip and ring conductors in the jack are wired behind the key-system line circuits. This arrangement is typically used when the modem doesn't require central office or PBX ringing to function properly.


Single Tie Trunk, Type I or II E&M interface, 8 position.


Single-line, 4-wire, T/R, T1/R1, 6-position.


Single-line, 2-wire, T/R, 6 position.


Two-line , 2-wire, T/R, T(MR)/R(MR), T(OPS)/R(OPS) 6-position.


Two-line, T1/R1, T2/R2, with sliding cover, 6-position.


Single-line, T/R, weatherproof, 3-position.


Single-line, T/R, used in hospital critical care areas, 6-position.


Single-line, T/R, with Make Busy leads, 6 positions .


12 lines, 4 wire, T/R, T1/R1, 50 positions.


12 Tie trunks, 2-wire, T/R, E&M Type I, 50 position.


8 Tie trunks, 2-wire, T/R, E&M SG/SB Type II 50 position.


8 Tie trunks, 4-wire, T/R, T1/R1, E&M, Type I 50 position.


6 Tie trunks, 4-wire, T/R, T1/R1, E&M, SG/SB, Type II, 50 positions.


12 lines, 2-wire, T/R, Make Busy leads, 50 position.


25 lines, 2-wire, T/R, 50 position.


3 lines, 2-wire, T/R, T (MR)/R(MR), T(OPS)/R(OPS), 6 position.


8 lines, 2-wire, T/R, FLL, or Programmed data, 50 position.


8 lines, 2-wire, T/R, Programmed Data, 50 position.


Single-line, 2-wire, T/R, MB/MB1, PR/PC, with Make Busy. 8 position, keyed and programmed.


Up to 8 multiple installations of FLL or Programmed Data. 8 position, keyed.


Single-line, 2-wire, T/R, FLL or Programmed Data, 8 position, keyed.


Up to 8 multiple installations of Programmed Data. 8-position, keyed.


Single-line, 2-wire, T/R, PR/PC, programmed data, 8 position, keyed.


Single-line, 4-wire, T/R, T1/R1, 1.544 Mbps, 8 position.


Up to 12 lines. 4-wire, T/R, T1/R1, 1.544 Mbps, 50 position.


Up to 8 lines, 4-wire, T/R, T1/R1, 1.544 Mbps, 50 position.


One or two lines. T/R or T/R, T1/R1, LADC or subrate. 8-position, keyed.


Up to 25 (2-wire) or 12 (4-wire), T/R OR T/R, TI/R1; LADC or Subrate,50-position.


Single-line, 4-wire, T/R, T1/R1, 1.544 Mbps, 8-position with shorting bar.


Up to 4 lines, T/R, 8-position.


Single private line, 2/4 wire, T/R or T/R, T1/R1, Non-registered service, 8-position, keyed, w/wo loopback.


This jack is normally associated with a telephone company-provided key telephone system. It's typically used with registered ancillary devices such as conferencing devices, music on hold, etc., and is wired to provide the same tip, ring, A, and A1 appearances as a standard five-line key telephone set.


RJ-25C provides for bridged connection to the tip and ring conductors of three separate telephone lines. The telephone company will wire the lines to the jack in the sequence designated by the customer. The RJ-25C is surface- or flushmounted for use with the desk telephone sets and ancillary devices.


An RJ-26X is a multiple-line universal data jack for up to 8 lines in a 50-position miniature ribbon connector and accommodates either fixed-loss loop (FLL) or programmed (P) types of data equipment. A switch, accessible to the customer, is provided on each line to select FLL or P type of operation. FLL equipment transmits at -4 + 1 dB with respect to one milliwatt and a pad is included in the data jack so that pad loss plus loop loss is nominally 8 dB. Programmed-type data equipment adjusts its output power in accordance with a programming resistor in the data jack. By these means, signals from either FLL or P types of registered data equipment will arrive at the local telephone company central office at a nominal -12 dB with respect to one milliwatt for optimum data transmission.


An RJ-27X is a multiple-line programmable data jack for up to 8 lines in a 50- position miniature ribbon connector and accommodates programmed data equipment only.


An RJ-31X provides a series connection to the tip and ring conductors of a telephone line. It's wired ahead of all station equipment electrically and is typically used with registered alarm-reporting devices. When there's an alarm condition, the registered device functions to cut off all station equipment wired behind it, via this jack.


Provides a series connection to the tip and ring conductors of a telephone line.

RJ-ICX Single Tie Trunk, Type I or II E&M interface, 8 position. RJ-IDC Single-line, 4-wire, T/R, T1/R1, 6-position. RJ-11C/W Single-line, 2-wire, T/R, 6 position.

RJ-14C/W Two-line, 2-wire, T/R, T(MR)/R(MR), T(OPS)/R(OPS) 6-position. RJ-14X Two-line, T1/R1, T2/R2, with sliding cover, 6-position.

RJ-15C Single-line, T/R, weatherproof, 3-position.

RJ-17C Single-line, T/R, used in hospital critical care areas, 6-position. RJ-18C/W Single-line, T/R, with Make Busy leads, 6 positions.

RJ-2DX 12 lines, 4 wire, T/R, T1/R1, 50 positions.

RJ-2EX 12 Tie trunks, 2-wire, T/R, E&M Type I, 50 position. RJ-2FX 8 Tie trunks, 2-wire, T/R, E&M SG/SB Type II 50 position. RJ-2GX 8 Tie trunks, 4-wire, T/R, T1/R1, E&M, Type I 50 position. RJ-2HX 6 Tie trunks, 4-wire, T/R, T1/R1, E&M, SG/SB, Type II, 50 positions. RJ-2MB 12 lines, 2-wire, T/R, Make Busy leads, 50 position.

RJ-21X 25 lines, 2-wire, T/R, 50 position.

RJ-25C 3 lines, 2-wire, T/R, T (MR)/R(MR), T(OPS)/R(OPS), 6 position. RJ-26X 8 lines, 2-wire, T/R, FLL, or Programmed data, 50 position. RJ-27X 8 lines, 2-wire, T/R, Programmed Data, 50 position.

RJ-4MB Single-line, 2-wire, T/R, MB/MB1, PR/PC, with Make Busy.

8 position, keyed and programmed.

RJ-41M Up to 8 multiple installations of FLL or Programmed Data.

8 position, keyed.

RJ-41S Single-line, 2-wire, T/R, FLL or Programmed Data, 8 position, keyed. RJ-45M Up to 8 multiple installations of Programmed Data. 8-position, keyed. RJ-45S Single-line, 2-wire, T/R, PR/PC, programmed data, 8 position, keyed. RJ-48C Single-line, 4-wire, T/R, T1/R1, 1.544 Mbps, 8 position.

RJ-48H Up to 12 lines. 4-wire, T/R, T1/R1, 1.544 Mbps, 50 position. RJ-48M Up to 8 lines, 4-wire, T/R, T1/R1, 1.544 Mbps, 50 position. RJ-48S One or two lines. T/R or T/R, T1/R1, LADC or subrate.

8-position, keyed.

RJ-48T Up to 25 (2-wire) or 12 (4-wire), T/R OR T/R, TI/R1; LADC or Subrate,50-position.

RJ-48X Single-line, 4-wire, T/R, T1/R1, 1.544 Mbps, 8-position with shorting bar.

RJ-61X Up to 4 lines, T/R, 8-position.

RJ-M8 Single private line, 2/4 wire, T/R or T/R, T1/R1, Non-registered service, 8-position, keyed, w/wo loopback.

It differs from RJ-31X in that it's wired ahead of a particular telephone set rather than ahead of all the station equipment. It's typically used with registered automatic dialers.


Is normally associated with a key telephone system. It provides a series connection to the tip and ring conductors of the telephone line and the key- system lien circuit A and A1 leads. The tip and ring conductors are wired ahead of the key-system line circuit. This arrangement is typically used when the modem requires central office or PBX ringing.


Is normally associated with a key telephone system. It's wired to provide a series connection to the key-system line circuit tip and ring conductors and it's a and A1 leads. It differs from RJ-33X in that all conductors are wired behind the key-system line circuit. This arrangement is typically used when the modem is not critical as to type of ringing signal or doesn't require central office or PBX ringing.


Is normally associated with a key telephone set. It's wired to provide a series connection to the tip and ring conductors of the telephone line and a bridged connection to the A and A1 leads. It differs from RJ-33X and RJ-34X in that the tip and ring leads are connected to the common wiring behind the pickup keys of the station set but ahead of the switch hook. The jack is wired to the key telephone set so that the modem functions on the line selected on the key telephone set.


Provides a connection for a registered telephone set equipped with an exclusion key when the telephone line is also to be used with a registered data set or registered protective circuitry . It's wired to provide a series connection to the tip and ring conductors of the telephone line and mode- indication leads MI and MIC. With this jack, the exclusion key can be used to transfer the telephone line between the modem and the telephone set. As a customer option, the exclusion key may be wired so that either the telephone set or the modem controls the line. In the former case, the exclusion key must be operated to transfer the telephone line to the modem. In the latter case, the telephone line is normally associated with the modem. Operation of the exclusion key is required to transfer the line to the telephone set. In either case, a closure on the MI and MIC leads indicates the voice mode.


Is used for providing two-line service with exclusion. The jack is wired to provide a bridged connection to the tip and ring conductors of two telephone lines with exclusion on line 1.


Provides a series connection to the tip and ring conductors of a telephone line identical to those described for RJ-31X. However, the jack also provides a continuity circuit which is used as an indication that the plug of the registered equipment is engaged with the jack. The jack is wired ahead of all station equipment electrically and is typically used with registered alarm dialers.

RJ-41M and RJ-45M

Provide a multiple-mounting arrangement for mounting a number of RJ-41S or RJ-45S Single-Line Universal or Programmed data jacks. The telephone companies will terminate USOCs, RJ-41M and RJ-45M with RKM2X (which is the USOC equivalent for a mounting arrangement) and the appropriate number of RJ-41S or Rj-45S single-line data jacks as required by the user. The mounting arrangement will accommodate up to 16 single- line data jacks. In effect, this arrangement provides the features of a patch panel. The user has complete flexibility in patching the color and plug from any modem to any line. The arrangement can be mounted on a wall or on 19- or 23-inch relay racks.


Is a single-line universal data jack normally associated with fixed-loss loop (FLL) or programmed (P) modems. A switch, accessible to the user, is provided to select FLL to P type of operation (FLL equipment transmits at - 4 dB with respect to one milliwatt, and a pad is included in the data jack so that pad loss plus loop loss is nominally 8 dB Programmed modems adjust their output power in accordance with a programming resistor in the data jack. By these means, signals from either FLL or P types of registered modems will arrive at the local telephone company central office at a nominal -12 dB with respect to one milliwatt for optimum data transmission.) A sliding cover is provided to keep dirt and dust from entering the jack when it's not in use. The FLL/P switch selects the desired method of operation. Two matted surfaces are provided on the housing of the jack for the telephone company installer to write in the loop loss (designated LPL) and the telephone line number (designated TLN).


The RJ-45 is the 8-pin connector used for data transmission over standard telephone wire. That wire could be flat or twisted. And it's very important that you know what you're working with. You can easily use flat wire for serial data communications up to 19.2 Kbps. Up to that speed you're connecting with your wire to a data PBX, a modem, a printer or a printer buffer. If you wish to connect to a 10Base-T local area network, which you also do with a RJ-45, you must use twisted wire. You can typically tell the difference by looking at the cable. If it's flat grey satin (like a typical phone wire, only bigger) than it's probably untwisted. If it's circular, then it's probably twisted and therefore good for LANs. RJ-45 connectors come into two varieties ” keyed and non-keyed. Keyed means that the male RJ-45 plug has a small, square bump on its end and the female RJ-45 plug is shaped to accommodate the plug. A keyed RJ-45 plug will not fit into a female, non-keyed (i.e. normal) RJ-45. See RJ-11 and RJ-22.


Is a single-line data jack normally associated with programmed (P) modems. This jack is the same as the universal data jack RJ-41S described above, except that the pad for fixed loss loop (FLL) equipment and the switch to select FLL or P type of operation are omitted. Its appearance is the same as RJ-41S except that RJ-45S does not have the FLL/P switch. Both jacks provide bridged connections to the tip and ring of a telephone line and provide mode-indication leads for use with exclusion key telephone sets when required. The exclusion key telephone set requires a series jack RJ-36X as its normal means of connection.


An 8-position keyed plug most commonly used for connecting T-1 circuits. The RJ-48C is an 8-position plug with four-wires (two for transmit, two for receive) commonly connected. When the phone company delivers T-1 to your offices, it usually terminates its T-1 circuit on a RJ-48C. And it expects you to connect that RJ-48C to your phone system or T-1 channel bank and then to your phone system.


Normally associated with DDS services from the telephone company, this jack is used with DDS CSU/DSUs.


An RJ-71C provides a multiple series arrangement of tip and ring. It's typically used with registered series devices such as toll restrictors, etc. Jack RJ-71C can accommodate up to 12 circuits per jack (i.e., one tip and ring "in" and one tip and ring "out", 4 leads per circuit). This arrangement does not currently provide restoration upon disconnection of registered equipment. Thus, a manual bridging plug is provided in order to maintain circuit continuity upon withdrawal of a registered plug.


A coaxial cable with a transmission impedance of 50 ohms. It's largely used for data, not video. See also RJ-58.

RJ-A1X and RJ-A3X

RJ-A1X and RJ-A3X are adapters used to adapt 4- and 12- position jacks, respectively, to a 6- position miniature bridged jack. They provide bridged connections to the tip and ring of the telephone line. If A and A1 leads are already terminated in the 4- or 12-pin jack, they will appear in positions 2 and 5 in the adapter. If A and A1 leads are not involved, positions 2 and 5 are reserved for telephone company use.


An RJ-A2X is an adapter that coverts a single miniature jack to two miniature jacks. It provides a bridged connection to the tip and ring conductors of the telephone line. If A and A1 leads are already terminated in an existing miniature bridged jack, they will appear in positions 2 and 5 both miniature bridged jacks in the adapters. If A and A1 leads are not provided, positions 2 and 5 are reserved for telephone company use.


See RJ-A1X.


Remote Job Entry. A Remote Job Entry terminal is used for the transmission of "batch" data to a remote computer system. Processed information is then returned to the printer in the terminal. This type of processing from a remote site is a standard method of data transmission. See IBM.


Registered Jack.


ReLease Complete message. The sixth ISUP call set-up message. A message sent in either direction in response to the receipt of a Release Message, or if appropriate to, a Reset Circuit Message when the circuit concerned has been brought into the idle condition. See ISUP and Common Channel Signaling.


Remote Line Concentrating Module.


Remote Live Call Screening. A Panasonic phone feature. RLCS is even better than live call screening feature. It lets you plug a single cordless phone into the External Data Port (XDP) on your Panasonic phone and monitor incoming voice mail remotely. When a call ends up in voice mail you use your cordless phone to screen your call. To take the call simply hit the same key again. This way you are always assured you will receive the important call you were waiting for ” even if you're in a meeting. This feature is only available on the Panasonic Super Hybrid PBX with its integrated digital Panasonic voice mail system. But I liked the feature enough to include it in my dictionary.


See Run Length Encoding.


Rural Local Exxchange Carrier. Defined by the FCC as an independent phone company serving rural communities, small towns, etc but could be adjacent to a major metropolitan area. Government protects these companies by making them permitted monopolies which are extremely difficult to compete with both because of government regulation and economics. Cetain rules apply which determine whether or not an ILEC qualifies as a RLEC.


  1. Radio in the Local Loop. Another term for WLL (Wireless Local Loop). RLL/WLL is a means for CLECs to deploy local loop capability rapidly , bypassing the incumbent LEC in the process. SEE WLL AND CLEC for more detail.

  2. Run Length Limited. A type of data coding used for disk drives . The term Run Length Limited derives from the fact that the techniques limit the distance (run length) between magnetic flux reversals on the disk platter. An RLL certified hard drive can use an MFM controller card but the storage capacity and the data transfer rate will be reduced.


Rlogin is an application that provides a terminal interface between UNIX hosts using the TCP/IP network protocol. Unlike Telnet, Rlogin assumes the remote host is (or behaves like) a UNIX machine.


Radio Link Protocol.


Receive Loudness Rating.


Release. You find a button labeled RLS on many phones. It means to hang up, or to end the call that you're presently on.


Release Link Trunks.


Resource Management. A mechanism used by the explicit-rate flow control scheme defined by the ATM Forum. Special control cells are used for explicit rate marking, with those cells taking up as much 3% of the network capacity, but serving to quickly convey information about network congestion back to the source (transmitting device). Explicit rate marking requires that the ATM switch mark the ABR RM (Available Bit Rate Resource Management) cells with the maximum transmission speed which can be supported over a VC (Virtual Circuit). Refer to RM- cell .


An ATM term. Resource Management Cell: Information about the state of the network-like bandwidth availability, state of congestion, and impending congestion, is conveyed to the source through special control cells called Resource Management Cells (RM- cells).


Returned Merchandise Authorization. A code number provided by the seller as a prerequisite to returning product for either repair or refund. An indispensable tracking procedure, it operates like a purchase order system. If you return computer or telephone equipment without an RMA number, chances are that it will be lost. The manufacturer will deny they ever received it. And you will be out of pocket and blamed. RMA is also called a Return Authorization (RA) number.


Remote Memory Administration System.


Remote Maintenance and Test System. That equipment and programming used to run, maintain and test a telephone system remotely ” usually by dialing in on a special phone line.


Remote MONitoring specification. A simple network management protocol used to manage networks remotely. It provides multi vendor interoperability between monitoring devices and management stations . RMON, is a set of SNMP-based MIBs (Management Information Bases) that define the instrumenting, monitoring, and diagnosing of local area networks at the OSI Data-Link layer. In IETF RFC 1271, the original RMON, which is sometimes referred to as RMON-1, defines nine groups of Ethernet diagnostics. A tenth group, for Token Ring, was added later in RFC 1513. RMON uses SNMP to transport data. To be RMON-compliant, a vendor need implement only one of the nine RMON groups. See MIB, RMON-2, RMON Probe, RMON Token Ring and SNMP.


The second Remote MONitoring MIB standard, called RMON-2, defines network monitoring above the Data-Link layer. It provides information and gathers statistics at the OSI Network layer and Application layer. Unlike the original RMON, RMON-2 can see across segments and through routers, and it maps network addresses (such as IP) onto MAC addresses. RMON-2 is currently a proposed standard under IETF RFC 2021. To be compliant with RMON-2, a vendor must implement all the monitoring functions for at least one protocol. RMON-2 does not include MAC-level monitoring, and thus it is not a replacement for the original RMON. See RMON.

RMON Groups

The original IETF proposed standard for the RMON MIB, RFC 1271 defines nine Ethernet groups: Ethernet Statistics, Ethernet History, Alarms, Hosts, Host Top N ("N" indicates that it collects information on a number of devices), Traffic Matrix, Filters, Packet Capture, and Events. RFC 1513 extends this standard to support Token Ring. See MIB, RMON, RMON Token Ring. b

RMON Probe

Sometimes called an RMON agent, an RMON probe is either firmware built into a specific network device like a router or switch, or a specific device built for network monitoring and inserted into a network segment. An RMON probe tracks and analyzes traffic and gathers statistics, which are then sent back to the monitoring software.

Historically, an RMON probe was a separate piece of hardware, but now RMON firmware is embedded in high-end switches and routers. See RMON.

RMON Token Ring

IETF proposed standard RFC 1513 is an extension to the original RMON MIB (RFC 1271), with support for Token Ring. Some sources refer to this standard as RMON TR, but it's generally considered a replacement for the older standard. In RFC 1513, the RFC 1271 Statistics and History monitoring groups have additional specifications for Token Ring, and a tenth group is added to monitor ring configuration and source routing. In 1994, the proposed standard became a draft standard under the designation RFC 1757; many vendors use the RFC 1513 and 1757 numbers interchangeably. See MIB, RMON.


See Roving Monitor Port.


See Repairman Revisit.


Root Mean Square. Method of measuring amplifier power.


Remote Measurement System Digital 1.


Remote Mask Unit.


  1. Ring No Answer: Open state in modem or Out of Band (OOB) diagnostic troubleshooting. Occurs when the remote modem is in a hung state and refuses to train (synch up) when prompted by an incoming call / request. When the modem "trains," it's establishing connectivity with the inbound RTS/CTS transaction.

  2. Remote Network Access. Another term for RAS, Remote Access Server.


Radio Network Controller.


Reserved Number Charge.


Abbreviation for not ready to receive.


  1. Receive Only.

  2. An ATM term. Read-Only: Attributes which are read-only can not be written by Network Management. Only the PNNI Protocol entity may change the value of a read-only attribute. Network Management entities are restricted to only reading such read-only attributes. Read-only attributes are typically for statistical information, including reporting result of actions taken by auto-configuration .


Recognized Operating Agency. An ITU (International Telecommunications Union) term. Any operating agency which operates a public correspondence or broadcasting service and upon which the certain obligations are imposed by the member state (i.e., nation) in whose territory the head office of the agency is situated, or by the member state which has authorized this operating agency to establish and operate a telecommunication service on its territory. An Operating Agency (OA) is defined as any individual, company, corporation or governmental agency which operates a telecommunication installation intended for an international telecommunication service or capable of causing harmful interference with such a service. Examples of ROAs are AT&T, Deutsche Telekom, Telstra, and MCI Worldcom.

Roach Theory

Coackroaches have this wonderful characteristic. Kill one. Another seems to come along. Kill that one. Another one appears. When bad news starts coming from a company you're invested in, more bad news often follows. Then bad news often follows . Bad news is not something that seems to happen in a vacuum . Wags on Wall Street have called bad news the Roach Theory. When you get a little bad news, you often get more and more, just like roaches.

Road Kill

Road kill is an awful name for the dead animals we see along the roads and highways, killed by passing motorists. In the language of the wired world, road kill are companies that don't make it. They may be killed by their own stupidity or they may be killed by their largest competitor dropping his prices dramatically. See also Road Pizza.

Road Map

Software that enables easier navigation to information desired. Especially helpful for Internet users.

Road Pizza

Companies who get run over by their competitors . Also a code name for a previous new product from Apple Computer.

Road Warrior

A businessperson who travels ...a lot. The road warrior's office is an airplane seat or a hotel room, and his weapons are a laptop with modem, wireless 802.11 hardware and communications software, a pager or Blackberry, a cell phone. Road warriors have a love/hate relationship with the "road."


Slang for legislation, or lack thereof, which inhibits rather than promotes the growth of the markets using interactive multimedia.


Any company trying to dominate the information highway through control of pieces of the infrastructure.


Robust Open Architecture Distributed Switching.

Roamer Fraud

Roamer fraud is the illegal use of another carrier's service without being charged. See Roaming.


Using your cellular phone in a city besides the one in which you live. Roaming usually incurs extra charges. Roaming prices may or may not be at a premium to local home area prices. See Roaming Agreement.

Roaming Agreement

An agreement between wireless carriers that allows their subscribers to use their phones on other wireless carriers .

Roaming Dial-back

The ability of the Dialup Switch to dial-back the user at a roaming location.


The Roaming Operations working group of the IETF (Internet Engineering Task Force). Roamops is developing a standard to define an authentication method for Internet users and a billing process across ISPs. The objective is to allow travelers to use a local ISP in another city or country, much like you can roam with your cell phone for an additional charge. If you use a local ISP, you currently must either place a long distance call to your local ISP's POP (Point of Presence), where your e-mail sits in a mailbox on his mail server ”much like you must place a long distance call to access your voice mail. Alternatively, you can use a national/international provider to gain access, or forward your e-mail from your local ISP to a national/international provider. All three of these alternatives are cumbersome, troublesome , and expensive, to say the least.

There also exist several roaming alliances which do the same thing, but on a proprietary basis. GRIC (Global Roaming Internet Connection) and I-Pass Alliance both act as clearing houses, much like a bank clearing house for ATM transactions, with each participating ISP setting its own rates for roaming transactions. The large telco ISPs, including both LECs and IXCs, also are establishing a proprietary roaming alliance. See also GRIC and I-PASS.

Robbed-Bit Signaling

This explanation from Gary Maier of Dianatel: ISDN is the key to future sophisticated telephone network services with its dynamic, highly configurable T-1 connection (also called PRI connection). Since T-1 is a common method of carrying 24 telephone circuits, many wonder about the uses for ISDN, especially when they learn ISDN signaling requires an entire voice channel, reducing today's T-1 from 24 voice channels to 23. But the popular signaling mechanism of "robbed bit" signaling in T-1 has serious limitations. Robbed bit signaling typically uses bits known as the A and B bits. These bits are sent by each side of a T-1 termination and are buried in the voice data of each voice channel in the T-1 circuit. Hence the term "robbed bit" as the bits are stolen from the voice data. Since the bits are stolen so infrequently, the voice quality is not compromised by much. But the available signaling combinations are limited to ringing, hang up, wink, and pulse digit dialing. In fact, the limitations are obvious when one recognizes DNIS and ANI information are sent as DTMF tones.

This introduces a problem: time. Each DTMF tone requires at least 100 milliseconds to send, which in a DNIS and ANI situation with 20 DTMFs will take at least two full seconds. There is also a margin for error in transmission or detection, resulting in DNIS or ANI failures. With the explosion of telephone related services, the telephone companies are turning to ISDN PRI to provide the more complicated and exact signaling required for new services. ISDN employs a more robust method of signaling. ISDN uses a T-1 circuit as 23 voice channels and one signaling channel. The term 23B plus D refers to 23 bearer (voice) channels and 1 Data (signaling) channel. The data channel carries the signaling information at a rate of 64 kilobits per second. This speed is many times greater than some of the most powerful modems available. Because of this high speed, telephone calls can be placed more quickly, and because of the protocol used, DNIS or ANI transmission failures are impossible .

Additionally, since no bits are "robbed" from the voice channels, the voice quality is better than that of Robbed Bit signaling on today's T-1 circuits. Also, computer modems and high speed faxes can use the voice channel for sending digital data instead of the traditional analog bit "noise." Therefore, ISDN PRI offers the end user countless new service capabilities. One channel could be used for faxing, another for modem data, several for video, another for a LAN and the remainder for voice. Suddenly, the average T-1 circuit becomes a pipeline for all communications! Increasingly long distance carriers are using ISDN PRI to provide inbound 800 calls with ANI and DNIS and re-routing skills. See Bit Robbing.


Remote Office / Branch Office market. See also SOHO and SOMO.


Automaton, or humanoid machine. From the Czech "robata," meaning "work." The idea first was introduced by Karel Capek in his 1921 play "R.U.R.," for "Rossum's Universal Robots." Science fiction writer Isaac Asimov made them famous with his 1950 story "I, Robot," and continuing through a series of books known as the "Robot Series." Robot has been abbreviated to "bot," meaning a software agent which does the bidding of its master (i.e., you) in accomplishing Web searches and such. Also called agent, spider and crawler. See also Bot.

Robot Virusing

hacking into an Internet-connected robot and infecting it with a virus. Wired magazine believes the proactice will spread as more businesses and homes begin using Web-controlled robot security systems.


A term used by telecommunications switch manufacturers to describe the alleged hefty quality of their network connections ” especially their switch-to-host links. The price of their link is often directly related to the number of times the manufacturer uses the word "robust" in a customer presentation.


Ring Operations Center. An ROC is telecommunications carriers' center that tests the circuits that that carrier is trying to turn up. The next generation after the NOC, the Network Operations Center.


The name of one of XM Satellite Radio's two satellites . The other is called Roll.

Rock Ridge Format

A set of CD-WO (write-once CDs) specifications to provide directory structures that may be updated as additional files are added. The specifications include: System Use Sharing Protocol (SUSP) and the Rock Ridge Interchange Protocol Specification (RRIPS). The specifications are extensions of the ISO 9660 format for CDROM. The SUSP extension to the ISO 9660 standard allows multiple file system extensions to coexist on one CD-ROM disc. The RRIP specification lets POSIX files and directories be recorded on CD-ROM without requiring modifications to files, such as shortening file and directory names.

Rodent Rubber

Another term for a B connector. See B Connector.


Regulatory commission authorized allowed rate of return on equity. See Revenue Requirement.


Abbreviation for "Rolling On the Floor, Laughing;" commonly used on E-mail and BBSs (Bulletin Board Systems).


As an adjective, it means bad. Rogue software is bad software ” software which would seriously hurt your computer. As a noun, rogue means scoundrel .

Rogue Buying

Rogue buying occurs when employees buy supplies for their company from unauthorized suppliers. The concept of rogue buying has enormous meaning for ecommerce. When companies set up Internet and Intranet links to their suppliers, they do electronic ordering, delivery tracking, inventory checking, etc. They save huge amounts of money ordering this way instead of the old way of calling on the phone, sending faxes, etc. When an employee buys from an unauthorized supplier, the company loses all the dollar savings benefits of the electronic ordering over the Internet or corporate Intranet. The solution is clearly to make the rogue supplier an authorized supplier and get him into the system. There is another solution: fire the employee. But that depends on if the supplier is ready with computers and networking. By the way, it can easily cost $150 to place an order the old way and less than $10 to place an order the new way, through ecommerce. Multiply that by thousands of orders per day for big companies and you can see the savings.

Rogue Software

See Rogue.


Receiver Off Hook.


Return On Investment.


Routing Over Large Clouds. Working group in IETF created to analyze and propose solutions to problems that arise when performing IP routing over large, shared media networks, such as ATM, Frame Relay, SMDS, and X.25. See IETF.

Role-Based Access Control



  1. Roll is the name of XM Satellite Radio's two satellites. The other is called Rock.

  2. See Let's Roll.

Roll About

A totally self-contained videoconferencing system consisting of the codec, video monitor, audio system, network interfaces and other components. These roll about systems can, in theory, be moved from room-to-room but in fact are not because they are electronic equipment that does not benefit from jostling. It's also heavy.

Roll Call Polling

A technique in which every station is interrogated sequentially by a central computer system.

Roll Call

A teleconferencing term. In a Dial-Out (operator-initiated) teleconference, the operator will announce each of the participants as he adds them to the conference bridge.

Roll Off Frequency

Corner frequency beyond which the attenuation increases rapidly.


A Web design page term. Imagine you're on a web site and you move your cursor over a piece of art, or even a blank spot. Suddenly, that piece of art changes and reveals an explanation or new menu, or some words or a new piece of art. A rollover is a piece of software which changes the appearance of objects when you roll over them. A rollover is also call a mouseover. See also Busy Out and Rollover Lines.

Rollover Lines

You receive many incoming calls. You don't want to miss a call, so you ask your phone company to set your phone lines up to roll over, also called hunt, also called ISG (Incoming Service Group) in telephonese. You order five lines in hunt. The calls come into the first. If the first one is busy, the second rings. If it's busy, the third rings. If they're all busy, then the caller receives a busy. The commonest types of hunting are sequential and circular hunting. Sequential hunting starts at the number dialed , keeps trying one number after another in number order and ends at the last number in the group. It's typically ascending. For example, it starts at 691-8215, goes to 691-8216, then 691- 8217, etc. But it can also be ascending ” from 691-8217 up. Circular hunting hunts all the lines in the hunting group, regardless of the starting point. Circular hunting, according to our understanding, circles only once (though your phone company may be able to program it circle a couple of times). The differences between sequential and circular are subtle. Circular seems to work better for large groups of numbers. You don't need consecutive phone numbers to do rollovers. Nowadays you can roll lines forwards, backwards and jump around, for example most idle, least idle. Rollovers are now done in software. This also has its downside, since software fails. For example, theoretically if a rollover strikes a dead trunk, it should bounce to the next live trunk. But sometimes it hangs on the dead trunk and many of your incoming calls never get answered . They might ring and ring. They might hit a busy. My recommendation: Test your rollovers at least twice a day. In particular, test that your callers ultimately get a busy if all your lines are busy. Nothing worse your customer should receive a ring-no-answer or a constant busy when calling your company. See also Terminal Number.


A telephone equipment manufacturer based in Santa Clara, CA, at least once upon a time. ROLM was started in 1969 by four engineers to produce computers for the military. The company introduced one of the first digital PBXs in 1975. It was a great PBX. Later, they developed a line of KTSs (Key Telephone Systems) and hybrid PBX/KTS systems. They were not so good. IBM acquired ROLM in 1984 as part of their plan to integrate the worlds of computers and communications. It didn't work...at all. And IBM lost a lot of money with Rolm. In 1989, IBM sold ROLM to Siemens, at which time it became ROLM Company. In 1994, the name was changed to Siemens Rolm Communication Inc. In 1996, the name was changed to Siemens Business Communication Systems, Inc. Siemens really doesn't use the name ROLM (or Rolm) anymore, but there are a lot of ROLM systems still in service.


A Trademarked product which started life as paper card based device to keep names and address on. Now it has become more of a generic name to connote software to let you look up peoples' phone numbers and addresses. Software to do this is also called PIM ” for Personal Information Manager.


Read Only Memory. Computer memory which can only be read from. New data cannot be entered and the existing data is non-volatile. This means it stays there even when power is turned off. A ROM is a memory device which is programmed at the factory and whose contents thereafter cannot be altered. In contrast is the device called RAM, whose contents can be altered . See Read Only Memory and Microprocessor.

ROM Font

The ROM Font is your PC's type font. It consists of a set of 256 characters which cannot be edited ” unless you are running in video mode, in which case you can design your own type font.

Rom Shadowing

386 and higher CPUs provide memory access on 32 & 64 bit paths. Often they will use a 16 bit data path for system ROM BIOS info . Also some adapter cards (ie. older video, network adapters etc.) with on board BIOS may use an 8 bit path to system memory. For high end computers this is a bottleneck. Like having YIELD signs out on the lanes within a freeway . ROM is very slow, 150ns-200ns. Modern RAM is 60ns or less. Therefore when the system is waiting on this data it generates wait states. For high end computers these wait states slow the entire system down. There is a system developed to transfer the contents of all the slow 8-16 bit ROM chips through out the system into 32 bit faster main memory. "This is ROM SHADOWING". This is accomplished using the MMU, the memory management unit. The MMU takes a copy of the ROM BIOS codes and places it into RAM. To the rest of the system this RAM location looks exactly like the original ROM location. This definition courtesy Charlie Irby, chasirby@foothill.net.


Romanji is a system of writing Japanese using the Latin alphabet.

R °ntgen, Wilhelm Conrad

A German scientist, (1845 - 1923), who fortuitously discovered X-rays in 1895.

Roofing Filter

A low-pass filter used to reduce unwanted higher frequencies.

Room Cut-Off

Hotel/motel guest telephones restricted from outgoing calls when the guest room is unoccupied.

Room Status And Selection

Provides the capability to store and display the occupancy and cleaning status and the type number of each guest room. This helps housekeeping management, maid locating and room selection. Also, communications between the front desk and the housekeeper are speeded up via real-time maid activity and checkout audit printouts to indicate which rooms need cleaning next. The occupancy status is normally changed by the maid or inspector dialing from the room telephone.


The base of a tree. The base of a hard disk. See Root Directory.

Root Account

Privileged account on UNIX systems used exclusively by network or system administrators.

Root Bridge

Exchanges topology information with designated bridges in a spanning- tree implementation to notify all other bridges in the network when topology changes are required. This prevents loops and provides a measure of defense against link failure.

Root CA

Ultimate Certificate Authority (CA), which signs the certificates of the subordinate CAs. The root CA has a self-signed certificate that contains its own public key.

Root Certificate

Certificate for which the subject is a root. Hierarchical PKI usage: The self-signed public-key certificate at the top of a certification hierarchy.

Root Directory

The top-level directory of a PC disk, hard or floppy. The root directory is created when you format the disk. From the root directory, you can create files and other directories.

Root Key

Public key for which the matching private key is held by a root.

Root Web

The FrontPage web that is provided by the server by default. To access the root web, you supply the URL of the server without specifying a page name. FrontPage is installed with a default root web named <root web>. All FrontPage webs are contained by the root FrontPage web.


Remote Operations Service Element. An application layer protocol that provides the capability to perform remote operations at a remote process. Definition from Bellcore (now Telcordia) in reference to its concept of the Advanced Intelligent Network.


A consortium of information technology, electronic components and semiconductor manufacturing companies working to create and implement open e-business process standards.

Rostered Staff Factor

RSF. A call center term. Alternatively called an Overlay, Shrink Factor or Shrinkage. RSF is a numerical factor that leads to the minimum staff needed on schedule over and above base staff required to achieve your service level and response time objectives. It is calculated after base staffing is determined and before schedules are organized, and accounts for things like breaks, absenteeism and ongoing training.


A call center term. The practice of rotating employees through all existing schedules in a matrix, or roster, of schedules. This "share the grief " method is prevalent in Europe and Australia, where agents work through an entire roster.


A way to encode things that the general Internet community can't read. Each letter in a message is replaced by the letter 13 spaces away from it in the alphabet. There are online decoders to read these. For instance, Harry Newton becomes Uneel Arjgba, which sounds a lot more exotic.


A call center term.

  1. An European term for a rotating shift pattern or rotating schedule,

  2. Short form for roster.

Rotary Dial

The circular telephone dial. As it returns to its normal position (after being turned) it opens and closes the electrical loop sent by the central office. Rotary dial telephones momentarily break the DC circuit (stop current flow) to represent the digits dialed. The circuit is broken three times for the digit 3. The CO counts these evenly- spaced breaks and determines which digit has been dialed. You can hear the "clicks". The number "seven," for example consists of seven "opens and closes," or seven clicks. You can dial on a rotary phone without using the rotary dial. Simply depress the switch hook quickly, allowing pauses in between to signify that you're about to send a new digit. It's a good party trick.

Rotary Dial Calling

The telephone system will accept dialing from conventional rotary dial sets.

Rotary Hunt

You buy several phone lines. Let's say 212-691-8215, 212-691- 8216, 212-691-8217, 212-691-8218. Someone dials you on your main number ” 212-691-8215. It's busy. (That's our number.) The central office slides the call over to 212-691-8216. If that number is busy, it slides it over to 212-691-8217, and so on. This is called rotary hunt. It hunts to the next line in the rotary group. In the old days, the phone lines you could rotary hunt to had to be in numerical sequence. But now with modern stored program control central offices, your lines in rotary hunt can be very different as long as they're all on the same exchange.

Rotary Output To Central Office

Most central offices are equipped to provide tone dial service. In cases where the telephone company central office trunks are not designed to accept tone signaling, your on premise phone system (PBX, key system or single line phone) will translate the number entered by a phone in tones into rotary dial pulses which can be processed by the central office.

Rotating Cylinder (Drum) Scanner

A scanning technique using a drum and a photocell scan head. The original is attached to the drum, enabling the scan head to travel along the length of the document. Reflected light from the document is concentrated on the scanner photocell, which causes an analog signal.

Rotating Helical Aperture Scanner

Original is illuminated by a lamp when fed onto the platen, via a mirror and lens system, the document's image is focused first through a fixed horizontal slot, then through a rotating spiral slit disk series, and finally onto a photocell to generate an analogous electrical current.

Rotational Latency

The delay time from when a disk drive's read/write head is on-track and when the requested data rotates under it.

Rotational Mailboxes

Information only mailboxes whose information is automatically changed on a time sensitive or usage sensitive basis.


I'm "Rolling on the Floor, Laughing." Used in e-mail.


  1. Remote Office Test Line. Provides the capability to originate automatic inter office trunk transmission test calls under the automatic control of CAROT from a remote location.

  2. A popular online abbreviation, shorthand for "Rolling On The Floor Laughing"; an appropriate typed response to a particularly amusing online remark. Other common Net acronyms include IMHO ("In My Humble Opinion") and IMNSHO ("In My Not-So-Humble Opinion").


The rotating part of a motor or other electrical machines.


Rotary Out-Trunk Switches.

Round Cutter

These are used to cut cables. The blades of the cutter are curved so that there is a space between them.

Round Robin

This is a method of distributing incoming calls to a bunch of people. This method selects the next agent on the list following the agent that received the last call. See also Top Down and Longest Available.

Round-Trip Time

See RTT.

Roundtrip Propagation Delay

Roundtrip propagation delay from a burst modem to a burst modem will be about 470 milliseconds to 570 milliseconds (About half a second). See Satellite Transmission Delay.

Routable Protocols

Protocols, such as TCP/IP, DECnet, and XNS, that support Network Layer addressing. Packets constructed using these protocols contain information about how data should move through a network. This information, carried in the NLA (Network Layer Address) field of the packet, is used by internetworking devices to make routing decisions.


The path that a message takes. In telephone companyese, a route is the particular trunk group or interconnected trunk groups between two reference points used to establish a path for a call. This term (or the term routing) is also used as a verb to define the act of selecting a route or routes.

Route 66

A colloquial term for the Internet, with something interesting everywhere along the way. Route 66 used to be the way we drove across America before they put in concrete highways.

Route Advance

This feature routes outgoing calls over alternate long distance lines when the first choice trunk group is busy. The phone user selects the first choice route by dialing the corresponding access code. The phone equipment automatically advances to alternate trunks and trunk groups, based on the user's class of service. Route advance is a more primitive form of least cost routing. See Least Cost Routing.

Route Caching

A type of load sharing in a which an application is assigned to a particular one of several parallel transmission circuits.

Route Control

Route control technology lets a company identify the most efficient ISP and sends Internet traffic to that ISP. Border Gateway Protocol (BGP) routes are continually updated by route control devices to maintain optimal traffic paths. This is how it works: Route control devices measure real-time, end to end performance for each ISP. Traffic flows over the fastest path, as determined by the route control device. Devices update BGP routes. ISP performance and traffic results are reported by the route control device.

Route Daemon

A program that runs under 4.2 or 4.3BSD UNIX systems (and derived operating systems) to propagate routes among machines in a local area network. Pronounced "route-dee."

Route Discovery

Process through which a brouter can learn LAN topology by passing information about its address and the LANs it connects and receiving the same information from others.

Route Diversity

See Diversity.

Route Flap

Route flap describes the impact of frequent changes in state (i.e., condition and availability) of Internet routes. The changes in state are generated by routers that sense (either correctly or incorrectly) that there are problems across one or more routes that connect them to their peers. In such an event, they generate route change messages that are sent to their peers. Route flaps can be caused by events such as BGP (Border Gateway Protocol) session resets between routers, changes in state (e.g., on or off) of a router, changes in state (e.g., up or down) of a circuit, changes in router filter lists, and high error rates over a particular link or circuit interconnecting two routers. These frequent changes cause a state of confusion as packets are routed first this way and then another way, like a flag flapping in the wind.

Route Guide

A map showing how calls are to be routed at the switch: first choice group of circuits, second choice, third choice, and fourth choice.

Route Hut

A physical site along the a route, particularly a fiber route, where the transmission is boosted.

Route Indexing

Provision of Interim Number Portability through direct trunks equipped for CCIS/SS7 operation, which are provisioned between end offices of Verizon and a CLEC. Inbound traffic to a ported number is routed over these trunks.

Route Indicator

An address or group of characters in the heading of a message defining the final circuit or terminal to which the message is to be delivered.

Route Length

The actual length of a route, or path, between transmitter and receiver. The length of the route is one factor that determines propagation delay, i.e., the delay associated with a signal as it transverses a network. Route length is determined by measuring the actual length of a the path, rather than the distance "as the crow flies."

Route List

A sequence of trunk groups that can be searched for a particular route. This list is comprised of trunk groups and configuration attributes (e.g. Class of Service) governing the use of a particular trunk group.

Route Mile

Let's say that you have two sheaths of fiber, each of which contains ten fibers and runs for one mile. That is one route mile (total distance of all fibers), two sheath miles (2 sheaths running one mile), and twenty fiber miles (20 fibers running one mile).

Route Optimization

  1. In voice communications, route optimistization is another another way of saying Least Cost Routing.

  2. In data communications ” such as the Internet - the concept refers to devices called route optimizers which peer into the Internet and fathom efficient ways of sending their information through it. Some route optimizers use the BGP ” Border Cateway Protocol. Other simpler ones take advantage of utilization thresholds, minimizing the need for BGP expertise. Route optimizers are used by webmasters especially when they maintain multiple, distant identical web servers. There's a fine art to using route optimizers on the Internet. They're often difficult to manage, but they're probably invaluable if you have a large network.

Route Server

An ATM term. A physical device that runs one or more network layer routing protocols, and which uses a route query protocol in order to provide network layer routing forwarding descriptions to clients .

Route Xpander Card

A board manufactured by IBM for insertion into a PC which provides the PC with a wide area interface to a frame relay network, including handling all of the necessary protocol encapsulation.

Routed Protocol

A protocol that can be routed by a router. To do so a router must understand the logical internetwork as perceived by that routed protocol. Examples of routed protocols include DECnet, AppleTalk, and IP.


  1. As in software, router is a system level function that directs a call to an application.

  2. As in hardware, routers are the central switching offices of the Internet and corporate Intranets and WANs. Routers are bought by everybody ” from backbone service providers to local Internet Service Providers (ISPs), from corporations to Universities. The main provider of routers in the world is Cisco. It has built its gigantic business on selling routers ” from small ones, connecting a simple corporate LAN to the Internet, to corporate enterprise wide networks, to huge ones connecting the largest of the largest backbone service providers. A router is, in the strictest terms, an interface between two networks.

Routers are highly intelligent devices which connect like and unlike LANs (Local Area Networks). They connect to MANs (Metropolitan Area Networks) and WANs (Wide Area Networks), such as X.25, Frame Relay and ATM. Routers are protocol-sensitive, typically supporting multiple protocols. Routers most commonly operate at the bottom 3 layers of the OSI model, using the Physical, Link and Network Layers to provide addressing and switching. Routers also may operate at Layer 4, the Transport Layer, in order to ensure endto-end reliability of data transfer.

Routers are much more capable devices than are bridges, which operate primarily at Layer 1, and switches, which operate primarily at Layer 2. Routers send their traffic based on a high level of intelligence inside themselves . This intelligence allows them to consider the network as a whole. How they route (also called routing considerations) might include destination address, packet priority level, least-cost route, minimum route delay, minimum route distance, route congestion level, and community of interest. Routers are unique in their ability to consider an enterprise network as comprising multiple physical and logical subnets (subnetworks). Thereby, they are quite capable of confining data traffic within a subnet, on the basis of privilege as defined in a policy-based routing table. In a traditional router topology, each router port defines a physical subnet, and each subnet is a broadcast domain. Within that domain, all connected devices share broadcast traffic; devices outside of that domain can neither see that traffic, nor can they respond to it. Contemporary routers have the ability to define subnets on a logical basis, based on logical address (e.g., MAC or IP address) information contained within the packet header, and acted upon through consultation with a programmed routing table. In addition to standalone routers developed specifically for that purpose, server-based routers can be implemented. Such routers are in the form of high-performance PCs with routing software. As software will perform less effectively and efficiently than firmware, such devices generally are considered to be less than desirable for large enterprise-wide application, although they do serve well in support of smaller remote offices and less-intensive applications. Routers also are self-learning, as they can communicate their existence and can learn of the existence of new routers, nodes and LAN segments. Routers constantly monitor the condition of the network, as a whole, in order to dynamically adapt to changes in network conditions.

Characteristics of routers can include: LAN Extension Store & Forward Support for Multiple Media Support for Multiple LAN Segments Support for Disparate LAN Protocols Filtering Encapsulation Accommodation of Various and Large Packet Sizes High- Speed Internal Buses (1+ Gbps) Self-Learning Routing Based on Multiple Factors Route Length Number of Hops Route Congestion Traffic Type Support for a Community of Interest (VLAN) Redundancy Network Management via SNMP

Router protocols include both bridging and routing protocols, as they perform both functions. Those protocols fall into 3 categories:

  1. Gateway Protocols establish router-to-router connections between like routers. The gateway protocol passes routing information and keep alive packets during periods of idleness.

  2. Serial Line Protocols provide for communications over serial or dial-up links connecting unlike routers. Examples include HDLC, SLIP (Serial Line Interface Protocol) and PPP (Point-to-Point Protocol).

  3. Protocol Stack Routing and Bridging Protocols advise the router as to which packets should be routed and which should be bridged.

This definition courtesy of "Communications Systems & Networks," the best-selling book by Ray Horak, my Contributing Editor. To buy the book, www.amazon.com. See also Bridges, Hubs, Internetworking and Switches.

Router-Based Firewall

A router-based firewall is a packet-filtering router. Not everyone agrees that a packet-filtering router alone is a firewall. Many people insist that only a system that includes a dual- homed gateway is a firewall. However, other people argue that a packet-filtering router is a firewall because the router meets important firewall criteria: The router is a computer through which incoming and outgoing packets must pass through which only authorized packets can pass.

Router Droppings

The inclusions added to e-mail messages when a server or recipient cannot be found. Cryptic and foul-looking, their meaning is usually impossible to fathom. Also called "daemon droppings."

Router Flapping

Router flapping occurs when a malfunctioning router keeps going in and out of service, forcing neighboring routers to keep updating their routing tables, until all of the processing power is being siphoned off and no traffic is being forwarded, resulting in an Internet brownout. This can occur on all types of backbones, regardless of the architecture, but routed IP networks, which deploy the most routers, are particularly vulnerable.

Router Protocols

Router protocols figure how A formula used by routers to determine the appropriate path onto which data should be forwarded. The routing protocol also specifies how routers report changes and share information with the other routers in the network that they can reach. A routing protocol allows the network to dynamically adjust to changing conditions, otherwise all routing decisions have to be predetermined and remain static.

Open shortest path first (OSPF). A routing protocol that determines the best path for routing IP traffic over a TCP/IP network. OSPF is an interior gateway protocol (IGP) that is designed to work within an autonomous system. It is also a link state protocol that provides less router to router update traffic than the REP protocol (distance vector protocol) that it was designed to replace.

Routing information protocol (RIl'). A simple routing protocol that is part of the TCP/IP P protocol suite. It determines a route based on the smallest hop count between source and destination. RIP is a distance vector protocol that routinely broadcasts routing information to its neighboring routers and is known to waste bandwidth.

Border gateway protocol (BGP). A routing protocol that is used to span autonomous systems on the Internet. It is a robust and scalable protocol that was developed by the Internet Engineering Task Force (IFTF). BGP4 supports the CEDR addressing scheme, which has increased the number of available IP addresses on the Internet. It is estimated that there are more than 60,000 I3GP routes currently on the Internet.

Classless interdomain routing (CIDR). A method for creating additional addresses on the Internet that are given to Internet service providers, which in turn delegate them to their customers. CIDR reduces the burden on Internet routers by aggregating routes, so that one IP P address represents thousands of addresses that are serviced by a major backbone provider. All packets sent to any of those addresses are sent to the ISP (e.g., MCI or Sprint). In 1990, there were about 2,000 routes on the Internet. Five years later, there were more than 30,000. Without CIDR, the routers would not have been able to support the increasing number of Internet sites.

Multiprotocol label switching (MPLS). A specification for Layer 3 switching from the IETF MPLS uses labels, or tags, that contain forwarding information, which are attached to packets by the initial router. The switches and routers down the road examine the label more quickly than if they had to look up a destination addresses in a routing table. When fully implemented on the Internet, MPLS is expected to deliver the quality of service required to adequately support real-time voice and video as well as service level agreements ( SLAs) that guarantee bandwidth to customers.

Resource reservation protocol (RSVP). A communications protocol that signals to a router to reserve bandwidth for real-time transmission. RSVP is designed to clear a path for audio and video traffic, eliminating annoying skips and hesitations. It has been sanctioned by the I ElF, because audio and video traffic is expected to increase dramatically on the Internet.

Router Rip

A Cisco term. This command enables the RIP (Routing Information Protocol) routing process on the router for TCP/IP.

Router Switches

A new breed of routers that in addition to routing TCP/IP packets (Internet packets) also routes cells, frames and other types of packets. See also Router.


A program, or a sequence of instructions called by a program, that has some general or frequent use.


The process of selecting the circuit path for a message.

Routing Area Subdomain

A cellular radio term. The combined geographic area of all Mobile Data Base Stations (MDBSs) controlled by a single Mobile Data Intermediate System (MD-IS).

Routing Code

  1. Another name for area code. See DN (as in directory number).

  2. The combination of characters or digits required by the switching system to route a transmission to its desired destination.

Routing Computation

The process of applying a mathematical algorithm to a topology database to compute routes. There are many types of routing computations that may be used. The Djikstra algorithm is one particular example of a possible routing computation.

Routing Constraint

A generic term that refers to either a topology constraint or a path constraint.

Routing Data Base

Distance table in DNA.

Routing Domain

Group of end systems and intermediate systems operating under the same set of administrative rules. Within each routing domain is one or more areas, each uniquely identified by an area address.

Routing Flexibility

The ability to send information over various network paths to avoid congestion and use portions of a total network that would otherwise be idle.

Routing Indicator

The address or routing code in the beginning of a message which specifies to the network the final circuit or destination of the message.

Routing Information Protocol

RIP is based on distance-vector algorithms that measure the shortest path between two points on a network, based on the addresses of the originating and destination devices. The shortest path is determined by the number of "hops" between those points. Each router maintains a routing table, or routing database, of known addresses and routes; each router periodically broadcasts the contents of its table to neighboring routers in order that the entire network can maintain a synchronized database. See also Distance vector Protocol.

Routing Label

The part of a signaling message identifying its destination.

Routing Metric

The method by which a routing algorithm determines that one route is better than another. This information is stored in routing tables. Such tables include reliability, delay bandwidth, load, MTUs, communication costs, and hop count.

Routing Number

pseudo Automatic Number Identification (pANI). A number employed in wireless E-911 call setup that can be used to route the call to an appropriate public service answering point (PSAP). The pANI generally identifies the cell/sector from which the call originates, whereas an ANI carries the actual telephone number of a wireline caller.

Routing Point

A location that a local exchange carrier has designated on its own network as the homing (routing) point for inbound traffic to one or more of its NPA-NXX codes. The Routing Point is also used to calculate mileage measurements for the distance- sensitive transport element charges of Switched Access Services.

Routing Point Port

This is the cornerstone term in CTI Link-based computer telephony, especially in call centers.

Routing Protocol

A general term indicating a protocol run between routers and/or route servers in order to exchange information used to allow figuring of routes. The result of the routing computation will be one or more forwarding descriptions. In short, a protocol that accomplishes routing through the implementation of a specific routing algorithm. Examples of routing protocols include BGP, CIDR, IGRP, MPLS, RIP, OSPF and RSVP. For a bigger explanation, see Route Protocols.

Routing Switcher

An electronic device that routes a user-supplied signal (audio, video, etc.) from any input to any user-selected output. Inputs are called sources. Outputs are called destinations.

Routing Table

  1. Incoming Phone Calls: A routing table is a user definable list of steps which are treatment instructions for an incoming call. Ideally these steps should be addressed and the call treatment begun before the call is answered. A routing table should consist of a minimum of steps that include agent groups, voice response devices, announcements (delay and informational) music on hold, intraflow and interflow steps, route dialing (machine based call forwarding). A significant issue in the structure of routing tables is "look-back" capability, where no one previously interrogated resource is abandoned by the system (i.e. an agent group is now ignored, even though an agent is now available, because the ACD does not consider previous steps in the routing table).

  2. Outgoing Phone Calls: For a specific calling site, this table lists the long distance routing choices for each location to be dialed. There may be only one choice (route) listed for some or all destinations or there may be several choices for some destinations. (It depends how many outgoing lines and how many outgoing trunk groups you have.) If there are several choices then they will be ranked by some criteria (least cost, best quality, etc.).

  3. In data communications, a routing table is a table in a router or some other internetworking device that keeps track of routes (and, in some cases, metrics associated with those routes) to particular network destinations. See Routing Metric.

Routing Transport Number

See RRN.

Routing Update

A message sent from a router to indicate network and associated cost information. Routing updates are typically sent at regular intervals and after a change in network topology.

Roving Monitor Port

Switch feature that lets you monitor network traffic on one or more ports via a third-party LAN packet analyzer. RMP can let you change the monitoring and monitored ports via software commands instead of via hardware changes.


In a table, a horizontal collection of cells.


A SMPTE parallel component digital video standard.


Remote Procedure Call.

  1. A protocol governing the method with which an application activates processes on other nodes and retrieves the results. A popular paradigm for implementing the client-server model of distributed computing. A request is sent to a remote system to execute a designated procedure, using arguments supplied, and the result returned to the caller. There are many variations and subtleties, resulting in a variety of different RPC protocols.

  2. A mechanism defined by Sun Microsystems and described in RFC-1057 that provides a standard for initiating and controlling processes on remote or distributed computer systems.


A sub-switch of a Main Switch-Usually located at another site (across the street, across town, across the country, etc.), but may be located at another end of the same building to conserve cabling. Connected with T-1 or other dedicated interconnections (DS- 3, DS-0 tie lines), often by T-1 over microwave (this is rapidly occurring over the Internet using IP). Allows for remote office phones to act as virtual extensions on the Main Switch.


Report Program Generator. A computer language for processing large data files.


Remote Packet Module.


  1. Routing Recording Number. This is the number AT&T assigns to a telephone circuit, especially T-1s, DS-3s, etc. This number is also referred to as an RTN, or Routing Transport Number. It is essentially the same as a BTN (Billed Telephone Number) except that the number is not necessarily an actual telephone number. The first three digits indicate which 4ESS or 5ESS digital switch the circuit is on, as well as whether it is 4ESS or 5ESS. The second three digits indicate the customer or trunk group the circuit is assigned to. The last 4 digits are, usually, the DNIS for that particular circuit. If, by chance, the customer does not have a DNIS, I believe AT&T will assign a random number for that particular circuit.

  2. Reverse Polish Notation. A calculator using RPN starts with the number you type in, then you hit enter, then you type in another number and the minus sign. Bingo, your screen shows the result of your calculation. In "normal" calculators you'd have to do another step, namely hit the enter button. Frankly, I prefer RPN. It's faster, easier and more logical. Most calculators don't come with RPN, sadly.


Recognized Private Operating Agency. A term used by the ITU-T to describe those companies designated as operating telephone companies ” if the country's phone networks are not run by government-owned administrations , such as the PTTs in Europe. A recognized Private Operating Agency is an organization that handles internetwork communications (e.g., long distance carriers). To identify some RPOAs, you must dial a prefix before your outgoing directory number. An RPOA can also refer to one or more DNICs that will connect two X.25 endpoints. For ISDN X.25, an RPOA is usually the DNIC for the ISDN's long distance carrier. See also ITU.


Request for Price Quotation. Solicitation for pricing for a specific component, software product, service or system. See also RFQ.


See Resilient Packet Ring. Emerging technology combines packet switched networks with dual rings. See Resilient Packet Ring.


Ring Protection Switching. Nortel's "Introduction to SONET Networking" tutorial handbook (www.nt.com/broadband/reference/sonet_101.html) talks about "Automatic Healing of Failed or Degraded Optical Spans in a Two-Fiber BLSR." The handbook says "in the event of failure or degradation in an optical span, automatic ring protection switching (RPS) reroutes affected traffic away from the fault within 50 milliseconds, preventing a service outage ."


Repair and Quick Clean. A term in the industry which repairs telecom equipment. It means all equipment is repaired and fully tested with a burn-in (if required) and an operational systems test. It also includes minor cosmetic cleaning of the unit. Definition courtesy Nitsuko America. See also Like New Repair and Update and Repair, Update and Refurbish.


Abbreviation for Ready to Receive.


Radio Resource Management.


Radio Resource Management Entity.


Routing Recording Number. This is the number AT&T assigns to a telephone circuit, especially T-1s, DS-3s, etc. This number is also referred to as an RTN, or Routing Transport Number. It is essentially the same as a BTN (Billed Telephone Number) except that the number is not necessarily an actual telephone number. The first three digits indicate which 4ESS or 5ESS digital switch the circuit is on, as well as whether it is 4ESS or 5ESS. The second three digits indicate the customer or trunk group the circuit is assigned to. The last four digits are, usually, the DNIS for that particular circuit. If, by chance, the customer does not have a DNIS, I believe AT&T will assign a random number for that particular circuit.


Restricted Radio Operator's Certificate of Proficiency. Certificate issued to those who successfully complete the Australian Communication Authority's Restricted Radio Operator's examination.


  1. Recommended Standard, as in RS-232.

  2. Record Separator, in data processing terms.

  3. An ATM term. Remote single-layer (Test Method): An abstract test method in which the upper tester is within the system under test and there is a point of control and observation at the upper service boundary of the Implementation Under Test (IUT) for testing one protocol layer. Test events are specified in terms of the abstract service primitives (ASP) and/or protocol data units at the lower tester PCO.

  4. Reduced Slope refers to the technical characteristics of optical fibers, specifically the dispersion slope which characterizes the chromatic dispersion of multiwavelength light in a wavelength multiplexed optical transmission path. For a much longer explanation, see Chromatic Dispersion.


The EIA (Electronics Industries Association) standard for the combination of signals required to form NTSC monochrome (black and white) video.


The EIA standard for the combination of signals required to form NTSC color video. It has the same base as RS-170, with the addition of color information.


Also known as RS-232-C and in its latest version EIA/TIA-232-E. RS-232 is actually a set of standards specifying three types of interfaces ” electrical, functional and mechanical. These are used for communicating between computers, terminals and modems. The RS-232-C standard, which was developed by the EIA (Electrical Industries Association), defines the mechanical and electrical characteristics for connecting DTE and DCE data communications devices. It defines what the interface does, circuit functions and their corresponding connector pin assignments. The standard applies to both synchronous and asynchronous binary data transmission. The most commonly used RS-232 interface is ideal for the data-transmission range of up to 20 Kbps for up to 50ft. It employs unbalanced signaling and is usually used with 25 pin D-shaped connectors (DB25) to interconnect DTEs (computers, controllers, etc.) and DCEs (modems, converters, etc.). Serial data exits through an RS-232 port via the Transmit Data (TD) lead and arrives at the destination device's RS-232-C port through the Receive data (RD) lead. RS-232-C is compatible with these standards: ITU V.24; ITU V.28, ISO IS2110. Most personal computers use the RS-232-C interface to attach modems. Some printers also use RS-232-C. You should be aware that despite the fact that RS-232-C is an EIA "standard," you cannot necessarily connect one RS-232-C equipped device to another one (like a printer to a computer) and expect them to work intelligently together. That's because different RS-232-C devices are often wired or pinned differently and may also use different wires for different functions. The "traditional" RS-232C plug has 25 pins. With the introduction of the IBM PC AT in the mid-1980s, most PCs and laptops switched to the "new" RS-232-C plug with only nine pins, called the DB-9. This smaller plug does essentially the same thing as its bigger cousin, but you need an adapter cable to connect one to another. They're widely available. See also interface and the RS-232-C diagram. See EIA/TIA-232-E and the APPENDIX for description of the pins and what they do. See also Crossover cable ” the name for a specially-wired RS-232 cable which allows two DTE devices or two DCE devices to be connected through serial ports and transmit and receive information across the cable. The sending wire on one end is joined to the receiving wire on the other. In an RS-232 cable, this typically means that conductors 2 and 3 are reversed .

RS-232 Fax Server

A RS-232 fax server is software which connects a network server to a fax machine via an RS-232 port attached to the fax machine. There are not many fax machines with R2-232 so you need to chose carefully . The idea of this arrangement is to let users send faxes directly from their own PC via the fax server via the attached fax machine, or directly from the fax machine. Users can also use the fax machine as a scanner.


In telecommunications, a transmission specification for NTSC video and audio.


October, 1966 the Electronic Industries Association issues its first fax standard: the EIA Standard RS-328, Message Facsimile Equipment for Operation on Switched Voice Facilities Using Data Communications Equipment. The Group 1 standard, as it later became known, made possible the more generalized business use of fax. Transmission was analog and it took four to six minutes to send a page.


An EIA interface standard for auto dialing.


Defines a balanced interface with no accompanying physical connector. Manufacturers who adhere to this standard use many different connectors, including screw terminals, DB9, DB25 with nonstandard pinning, DB25 following RS-530, and DB37 following RS-449. RS-422 is commonly used in point-to-point communications conducted with a dual-state driver. Transmissions can run long distances at high speeds. RS is a standard operating in conjunction with RS-449 that specifies electrical characteristics for balanced circuits (circuits with their own ground leads). RS-422 (now known as EIA/TIA-422) is a balanced electrical implementation of RS-449 for high-speed data transmission. RS stands for recommended standard. The RS-422 is also known as a V11.


Electrical characteristics of balanced-voltage digital interface circuits.


A standard operating in conjunction with RS-449 that specifies electrical characteristics for unbalanced circuits (circuits using common or shared grounding techniques). Another EIA standard for DTE/DCE connection which specifies interface requirements for expanded transmission speeds (up to 2 Mbps), longer cable lengths, and 10 additional functions. RS-449 applies to binary, serial, synchronous or asynchronous communications. Half- and full-duplex modes are accommodated and transmission can be over 2- or 4-wire facilities such as point-to-point or multipoint lines. The physical connection between DTE and DCE is made through a 37-contact connector; a separate 9-connector is specified to service secondary channel interchange circuits, when used.


Electrical characteristics of unbalanced-voltage digital interface circuits. RS- 423 (now known as EIA/TIA-423) is an unbalanced electrical implementation of RS-449 for RS-232-C compatibility.


RS-449 (now known as EIA/TIA-449) is essentially a faster (up to 2 Mbps) version of RS-232-C capable of longer cable runs. RS-449 is another "standard" data communications connector. It uses uses 37-pins and is designed for higher speed transmission. Each signal pin has its own return line, instead of a common ground return and the signal pairs (signal, return) are balanced lines rather than a signal referenced to ground. This cable typically uses twisted pairs, while a RS-232-C cable usually doesn't.

According to Black Box Corp, RS-449 defines functional/mechanical interfaces for DTEs/DCEs that employs serial binary data interchange, and is usually used with synchronous transmissions. It identifies signals (TD, RD, etc.) that correspond with the pin numbers for a balanced interface on DB37 and DB9 connectors. RS-449 was originally intended to replace RS-232-C, in order to improve data-transmission capabilities to up to 2 Mbps/200ft. (60M), reduce electrical "crosstalk," and accommodate additional signal functions. RS-232-C and RS-449 were to become interoperable by using electrical interface standards RS-422 and RS-423. But right now RS-232 and RS-449 are incompatible in terms of mechanical and electrical specifications. RS-449 is technically compatible with these standards: RS-530, V.10, V.110, and ITUT X.21 bis.


Resembles RS-422 except that associated drivers are tri-state, not dual-state. It may be used in multipoint applications where one central computer controls many different devices. Up to 64 devices may be interconnected with RS-485. RS-485 describes electrical characteristics of a balanced interface used as a bus for master/slave operation. Used in industry for the Process Field Bus, and in telco management networks.


Addendum 1 to RS-449. (What else?)


Supercedes RS-449 and complements RS-232. Based on a 25-pin connection, it works in conjunction with either electrical interface RS-422 (balanced electrical circuits) or RS-423 (unbalanced electrical circuits). RS-530 defines the mechanical/electrical interfaces between DTEs and DCEs that transmit serial binary data, whether synchronous or asynchronous. RS-530 provides a means for taking advantage of higher data rates with the same mechanical connector used for RS-232. However, RS-530 and RS-232 are not compatible. And RS-530 offers the benefits of RS-449 and the efficiency of a 25-pin design. It accommodates data transmission rates from 20 Kbps to 2 Mbps; maximum distance depends on which electrical interface is used. (RS-530 is compatible with these standards: ITU 10, V.11, X.26; MIL-188114; RS- 449.)


  1. Rural Service (or Statistical) Area. The FCC designated 428 rural markets across the United States and licensed two service providers per RSA. See also MSA.

  2. Rivest-Shamir-Adleman. A public key encryption algorithm invented in 1977 and named after its inventors. A large number algorithm, RSA is highly secure, as each user finds two large prime numbers ("p" and "q") which are then multiplied together ("p" x "q" = "n"). The public key is "n," and the private key is "p" and "q." RSA key sizes range from 768 to 2,048 bits. As a 2,048 bit key yields 2 to the 2,048th power possible combinations, RSA is highly immune to even the most persistent brute force security attacks. RSA Security Inc. offers a number of security tools based on the RSA core algorithm, of which over 75 million copies have been licensed. PGP (Pretty Good Privacy) incorporates the RSA core algorithm, as does SET (Secure Electronic Commerce). RSA core technologies are part of existing and proposed standards of ANSI, IEEE, ISO, and ITU. See also Digital Certificate, Encryption, PGP, Private Key, Public Key and Set.


See Repair Service Bureau.


Remote Switching Center.


Remote Switching Center-S.


An ATM term. Remote Single-layer Embedded (Test Method): An abstract test method in which the upper tester is within the system under test and there is a point of control and observation at the upper service boundary of the Implementation Under Test (IUT) for testing a protocol layer or sublayer which is part of a multi-protocol IUT.


An ATM term. Route Server Functional Group: The group of functions performed to provide internetworking level functions in an MPOA System. This includes running conventional interworking Routing Protocols and providing inter-IASG destination resolution.


Residential System IDentifier.


Request and Status Links. A generic term for linking computers and PBXs. Every manufacturer of phone systems is evolving towards open architecture and their own "RSL." The term RSL, which is too passive, is being replaced with PHI (PBX Host Interface), a term coined by Probe Research. Manufacturer PHI names include:

ACL ” Applications Connectivity Link ” Siemens' PHI link protocol

ACT ” Applied Computer Telephony ” Hewlett Packard's generic application interface to PBXs

Application Bridge ” Aspect Telecommunications' ACD to host computer link

ASAI ” AT&T's Adjunct Switch Application Interface

CIT ” Digital Equipment Corporation's Computer Integrated Telephony (works with major PBXs)

CSA ” Callpath Services Architecture ” IBM's Computer to PBX link

Call Frame ” Harris' PBX to computer link

Callpath Host ” IBM and ROLM's CICS-based integrated voice and data applications platform which links to ROLM's 9751

Callpath ” IBM's announced, CICS application link to IBM's CSA, available on the AS400 in April of 1991

Callbridge ” Rolm's CBX and Siemens to IBM host or non-IBM host computer link

CompuCall ” Nortel Networks' DMS central office link to computer interface

CSP ” Nabnasset's Communications Services Platform

CSTA ” Computer Supported Telephony Application, PHI standard from ECMA

DECags ” DEC ASAI Gateway Services. Two-directional link to AT&T's Definity

DMI ” AT&T's Digital Multiplexed Interface, a T-1 PBX to computer interface

HCI ” Host Command Interface. Mitel's digital PBX link to DEC computer

IG ” AT&T's ISDN Gateway (one direction from the switch to the host)

ITG ” AT&T's Integrated Telemarketing Gateway (two directional)

ISDN/AP ” NT's PHI SL1 protocol supports NT's Meridian Link PHI

Meridian Link ” NT's PHI product available on the Meridian PBX

OAI ” Open Application Interface. InteCom's and NEC's PHI

ONA ” Open Network Architecture (for telephone central offices)

PACT ” Siemens' PBX and Computer Teaming, protocols between PBXs and computers

PDI ” Telenova/Lexar's Predictive Dialing Interface

SAI ” Stratus Computer Switch Application Interface

SCAI ” Switch to Computer Application Interface, the name given by T1S1 to PHI

SCIL ” Aristacom's Switch Computer Interface Link Transaction Link

STEP ” Speech and Telephony Environment for Programmers; WANG's link

Transaction Link ” Rockwell's link from its Galaxy ACD to an external computer Solid State Applications Interface Bridge ” Solid's State Systems' PHI

Teleos IRX-9000 ” Teleos' Intelligent Call Distribution platform For more information, see OAI (Open Architecture Interface.)


  1. Remote Switching Module. An AT&T 5ESS switch standalone switching module that supports all line features and routes intro-RSM calls. It is either a single module or a multi module and can be situated up to 150 miles from the 5ESS switch host.

  2. Radio Sub-system Management. A wireless telecommunications term. Management of radio channels including timing and frequency as well as all machines between the mobile station and the MSC.


Remote Source Route Bridging. Source-route bridging over wide-area links.


Received Signal Strength Indication.


Rapid Spanning Tree Protocol.


  1. Remote Service Unit. A cable telephony term for a device installed at the customer premises. The RSU functions as a standard Network Interface Device (NID) for termination of the coaxial cable network, and the interface between the twisted pair inside wire and cable system inside the premises. Thereby, the coaxial cable network can support telephone service and high-speed Internet access, in addition to CATV service. The RSU performs the RF transceiver (transmitter/receiver), modulation/demodulation of the broadband RF (Radio Frequency) signals, multiplexing/ demultiplexing of the digital signals, analog-to-digital conversion (as required), signaling conversion for subscriber loop operation, and diagnostics for problem isolation. The unit provides a "virtual twisted pair" back to a local switching interface for transparent telephony operation of CLASS services and custom calling features. The RSU communicates with the Host Digital Terminal (HDT) at the head end of the CATV network. The RSU may be in the form of either an indoor or an outdoor unit, and may be powered either over the coax network or, more commonly, is powered locally powered through an A/C (Alternating Current) transformer at the customer premises. An RiSU (Remote indoor Service Unit), a variation on the theme, is locally powered and includes battery backup. A RSUM (Remote Service Unit Multiple) is used to provide service to a MDU (Multiple Dwelling Unit), such as an apartment complex, condominium , or multipurpose high-rise building. See also CATV and Network Interface Device.

  2. See Remote Switch Unit.


The Resource Reservation Protocol (RSVP) is an IETF standard designed to support resource (for example, bandwidth) reservations through networks of varying topologies and media. Through RSVP, a user's quality of service requests are propagated to all routers along the data path, allowing the network to reconfigure itself (at all network levels) to meet the desired level of service. The RSVP protocol engages network resources by establishing flows throughout the network. A flow is a network path associated with one or more senders, one or more receivers, and a certain quality of service. A sending host wishing to send data that requires a certain QoS will broadcast, via an RSVP-enabled Winsock Service Provider, "path" messages toward the intended recipients. These path messages, which describe the bandwidth requirements and relevant parameters of the data to be sent, are propagated to all intermediate routers along the path. A receiving host, interested in this particular data, will confirm the flow (and the network path) by sending "reserve" messages through the network, describing the bandwidth characteristics of data it wishes to receive from the sender. As these reserve messages propagate back toward the sender, intermediate routers, based on bandwidth capacity, decide whether or not to accept the proposed reservation and commit resources. If an affirmative decision is made, the resources are committed and reserve messages are propagated to the next hop on the path from source to destination.

The idea is that for presumably a premium price, RSVP will enable certain traffic, such as videoconferences, to be delivered before e-mail. Today, all traffic on IP networks moves on a first-come-first- served basis and is charged at a flat rate. "In some ways RSVP will change what the Internet is all about, because you'll start to have different qualities of service and differential prices which are new," said Abel Weinrib, a key Internet strategist for Intel Corp. Virtually unknown among the general Internet community, RSVP has been quietly pushing ahead towards becoming acceptable and popular. It is now part of Microsoft's TAPI 3.0. It is being pushed also by Cisco Systems Inc., which makes the routers that direct most Internet traffic, and by Intel, which wants to spur demand for microprocessors by making computers and IP networks more useful for uses like phone calls and video conferencing. In an article I read, Cisco marketing manager Peter Long said RSVP technology would be included in new network software Cisco is delivering. That software controls the routers that direct Internet traffic. Cisco sells more than 80 percent of the routers used in commercial and corporate Internets. Long expects Cisco customers to start using RSVP technology to create what he calls "diamond lanes" on the Internet. "Right now, if there is congestion on the Internet, your traffic sits there, like a car stuck on an onramp," Long said. He said RSVP would act like "a big crane that picks you up and puts you over the other cars ," onto these so-called diamond lanes that bypass congested parts of the Net. See TAPI 3.0.


  1. Reorder Tone.

  2. Remote Terminal. Local loop terminates at Remote Terminal intermediate points closer to the service user to improve service reliability.

  3. Remote Termination. A node at which terminates a high-capacity local distribution facility in a DLC (Digital Loop Carrier) scenario. The other end of the circuit is known as a COT (Central Office Termination). See also DLC.


Real Time ANI.


RunTime Control.


Real Time Conferencing Protocol. Supports real-time conferencing for large groups on the Internet. It has source identification and support for audio and video bridges/gate- ways. Supports multicast-to-unicast translators.


Rich Text Format. A way of encoding documents such that the messages include boldface, italics and other limited text stylings. RTF is meant to be a cross word processing platform such that if you send one RTF document (by email, for example) from one word processor to another word processor, that second word processor will be able to recreate the document's original format.


Read The Fantastic Manual. This acronym is often used when someone asks a simple or common question. The word "Fantastic" is usually replaced with an adjective much more vulgar. A friend wrote me about his new digital camera: "Downside is that it's so feature-rich, I often have to RTFM." RTFM is also used also on e-mail, newsgroups, and the Internet. See also Cockpit Problem, Idiot-Proof, and Intuitive.


Reference Transmission Level Point.


  1. Ready To Manufacture.

  2. Read The Manual.


Routing Table Maintenance Protocol. It is the native Appletalk routing protocol. It sends updates out every 10 seconds.


See RRN.


A British term. Ring Tone No Reply, a telephone call which has not been answered. Typically a telebusiness system will automatically re-dial the number after a pre-determined period.


Ready To Order - In Service.


Real-Time Operating System


  1. Realtime Transport Protocol. An IETF standard for streaming realtime multimedia over IP in packets. Supports transport of real-time data like interactive voice and video over packet switched networks. A thin protocol providing support for content identification, timing reconstruction, loss detection and security. The ARPA DARTnet transcontinental IP network experiments lead to RTPs popularity. Now championed by the Audio/Video Transport (AVT) Working Group. AVT is part of the IETF (Internet Engineering Task Force). RTP does not do resource reservation or quality of service control. It relies on resource reservation protocols like RSVP. See H.323.

  2. Routing Table Protocol. Used in Banyan VINES routing with delay as a routing metric.


Request To Send. One of the control signals on a standard RS-232-C connector. It places the modem in the originate mode so it can begin to send. See the Appendix.


Reliable Transfer Service Element. The OSI application service element responsible for transfer of bulk-mode objects.


Real Time Streaming Protocol. See Real Time Streaming Protocol.


  1. Radio Transmission Technologies. See G3.

  2. Round-Trip Time. Time required for a network communication to travel from the source to the destination and back. RTT includes the time required for the destination to process the message from the source and to generate a reply. RTT is used by some routing algorithms to aid in calculating optimal routes.


Remote Trunk Test Unit.


  1. Remote Termination Unit, Remote Telemetry Unit or Remote Terminal Unit. Basically an RTU is a little black box connected to some remote gadget. The RTU lets the gadget installed at one end of a analog circuit respond to commands that are sent to it over an analog, dial-up phone line. Imagine an oil pipeline. There's a leak. You have to shut the pipe off ” not only at the beginning of it. You have to shut it down at the spot closest to the leak, to minimize the spill. Thus you call that switch and tell it over the phone line and using the Remote Termination Unit at the switch to shut off. It does. Obviously there's also a big electrically driven device that physically turns the handle to shut the oil down.

  2. Right To Use. A term manufacturers have invented to stifle the used/secondary market in their equipment. Basically, the manufacturer says "Fine, you can sell your no-longer- needed product to some used equipment dealer. But if someone buys it from the dealer and wants to use it, they have to pay me a Right To Use fee." Without payment of this fee, the manufacturer won't contract to maintain the customer's equipment and certainly won't sell the customer software updates, etc. The right to use fee is exorbitant ” typically considerably more than what the product actually sells on the used market for. A better approach for a manufacturer would be to innovate a little more and make the customer wants his new product more than his old price (despite the old product's lower price).

  3. Remote Terminal (not terminating) Unit. RTUs are employed by utilities' SCADA (Supervisory Control And Data Acquisition) systems in electric substations or gas/water/ steam pumping plants to monitor status/condition and/or metering data and to control operations at a remote site. SCADA systems are not limited to distribution systems; SCADA is also used to manage transmission facilities. Distribution is local delivery to end customers; transmission is backbone transport facilities. The analogies between the electrical, water, gas, and telecommunications infrastructures /networks go on and on. See SCADA.


Real-Time Video. DVI software that implements quick-and-dirty, realtime video compression. Once called "edit-level video," it stores video as only 10 frames per second. Meant for use while developing DVI applications.


900 Blocking Option.


976 Blocking Option.


  1. Request Unit or Response Unit. A basic unit of data in SNA.

  2. Receive Unit

  3. Abbreviation of rack unit. See Rack Unit.

Rubber Bandwidth

A term coined by Ascend , an inverse multiplexer manufacturer, to refer to the ability to support applications needing varying speeds. It breaks the original signal up into 56- or 64-Kbps chunks , and places these separate transmissions on the public switched digital network. See also Inverse Multiplexer.

Ruby Test

Let's say you have a bundle of optic fibers inside a sleeve buried in the ground for miles or running inside a building. How do you figure out with great accuracy which fiber is the same at the one of the fiber as the other? Easy ” the Ruby Test. Send a strong ruby coloured light down the strand . See where it comes out the other end. Not very sophisticated, but it works.

Rulemaking Number

A number assigned to a proceeding after the appropriate Federal Communication Commission Bureau/Office has reviewed and accepted a Petition for Rulemaking, but before the Commission has taken action on the petition. The rule- making number should appear on all appropriate documents, even those which carry a docket number.

Rules-based Call Management

This a feature of some phone systems which enables the subscriber to pre-program rules specifying how they want their incoming and outgoing calls to be handled. The subscriber typically defines these rules using their browser over the Internet to speak to a server.

Rules Based System

The most popular way to represent knowledge in an expert system. In general, a rule-based system's knowledge base contains both facts and IF..THEN production rules.

Rule of Thumb

The phrase "rule of thumb" came from an old English law which made it illegal to beat your wife with anything wider than your thumb.


To start a software program.


On a Norstar phone, this feature inserts a delay in a dialing sequence. The delay can be any length of time.

Run Length Encoding

RLE. A form of data compression which is semantic- dependent in nature. Such techniques are designed to respond to specific types of local redundancy, such as image representation and processing. RLE is a common technique which involves the scanning of image elements along a scan line or row. As the device scans the image, it identifies redundant data and converts it into a code corresponding to the length of the run of such redundant data. A string of identical bits is indicated by sending only one example, preceded by a control character (e.g., *) and a shorthand description of the number of times it repeats. For example, the character string "HNBBBBBCDDDDEFFF" would be RLE Encoded as "HN*5BC*4DE*3F." The higher the level of redundancy for a particular data string, the greater the efficiency of the process. Fax machines use RLE, identifying runs of black or white dots on the page, encoding the length of the run of redundant data as they scan the document, a line at a time. The data is transmitted in compressed form, using this form of data shorthand, and the process is reversed by the receiving fax machine. The advantage, of course, is that the cost of the call is reduced considerably, as the transmission time is much less. This is particularly so in documents containing a lot of white space. RLE also is used in data processing applications to reduce the amount of processing time involved by compressing sequences of zeros or blanks in data fields. RLE also is used to compress memory-intensive files, such as bitmapped graphics. In such an application, the technique is especially useful for black-and-white or cartoon-style line graphics, as runs of the same color can be replaced with a single character. RLE files are identified by the ".rle" file extension. Commonly, .pcx files are run length encoded, as are .tiff and .bmp files; even though these files retain their own file extensions and formats. See also Compression.

Run Time

The time it takes to execute a software program. See Runtime.


An Ethernet frame that is shorter than the valid minimum packet length, usually caused by a collision. The term is imprecise, and may indicate a collision, collision fragments , a short frame with a valid FCS checksum, or a short frame with an invalid FCS checksum. In a litter of animals, the smallest and weakest animal is typically called the runt. Because the runt is weak, he/she usually ends up sucking his/her sucking hind tit ” the nipple that produces the least amount of food. A person who is small and contemptible is also called a runt. See also Runt Frame and Runt Packet.

Runt Frame

A small packet received with FCS or alignment errors. Runt frames are the result of collision occurring on connected segment or among stations connected to attached repeaters. See Runt and Runt Packet.

Runt Packet

A data packet with a legal shorter than required by the IEEE 802.3 standard of 64 bytes or 512 bits. See also Runt and Runt Frame.


  1. A computer term, usually used in the "heavy metal" world of mainframe computers. Runtime (or run time) is the amount of time it takes the CPU (Centralized Processing Unit) to execute a program or perform an operation.

  2. A runtime environment is the software that plays back multimedia materials. The runtime material is created by the author. Examples of runtime applications are presentations are training, where the material cannot be edited but only viewed . The runtime software could be a slide show viewer, a software-only video playback application, or a hyper- media runtime document. See Runtime License.

Runtime Control

RTC. An SCSA definition. The mechanism by which one Resource Object can influence the behavior of another. Typically used for things such as terminating conditions and speed/volume control.

Runtime License

A one-time or royalty-based fee paid for the inclusion of runtime code in a replicated product.


Repair, Update and Refurbish. A term in the industry which repairs telecom equipment. It means equipment is repaired and updated to current manufacturer's specifications. Also includes minor cosmetic cleaning of metal cabinets , a full diagnostic test with burn-in (if required) and an operational test. Definition courtesy Nitsuko America. See also Like New Repair and Update and Quick Clean.

Rural Health Care Corporation

RHCC. A not-for profit corporation formed by the Telecommunications Act of 1996, and operating as the Rural Health Care Division (RHCD) of the Universal Service Administrative Company (USAC), which also was formed by The Act. The RHCC is responsible for distributing up to $400 million per year of funds from the Universal Service Fund (USF). Those funds subsidize the cost of internal wiring, telecommunications services, and Internet access for rural health care organizations. See also Universal Service Administrative Company and Universal Service Fund.

Rural Service Area

RSA. An area not included in either an MSA or a New England Country Metropolitan Area for which a common carrier may have a license to provide cellular service.

Rural Telephone Company

The Telecommunications Act of 1996 defines a rural telephone company as a local exchange carrier operating entity to the extent that such entity ” (A) provides common carrier service to any local exchange carrier study area that does not include either ”

  1. any incorporated place of 10,000 inhabitants or more, or any part thereof, based on the most recently available population statistics of the Bureau of the Census; or (ii) any territory, incorporated or unincorporated, included in an urbanized area, as defined by the Bureau of the Census as of August 10, 1993;

  2. provides telephone exchange service, including exchange access, to fewer than 50,000 access lines;

  3. provides telephone exchange service to any local exchange carrier study area with fewer than 100,000 access lines; or

  4. has less than 15 percent of its access lines in communities of more than 50,000 on the date of enactment of the Telecommunications Act of 1996.


Rural Utilities Service. The successor to the REA (Rural Electrification Administration). The RUS is an agency of the U.S. Department of Agriculture (USDA). According to the USDA, "RUS is a vital source of financing and technical assistance for rural telecommunication systems." RUS also provides funding for electric and water programs through public/private partnerships designed to further rural infrastructure development. See also REA.


In the old days of Russian communism, they had an axiom of how business was meant to work, namely, "They pretend to pay us and we pretend to work."


Recorded Voice Announcement. Australian term for a recorded message advising that a number has changed.


See Revenue Volume Pricing Plan.


  1. An ATM term. Read-Write : Attributes which are read-write can not be written by the PNNI protocol entity. Only the Network Management Entity may change the value of a read-write attribute. The PNNI Protocol Entity is restricted to only reading such read-write attributes. Read-write attributes are typically used to provide the ability for Network Management to configure, control, and manage a PNNI Protocol Entity's behavior.

  2. Referring to CDs, when you see CD-R, it means that the name of the disc ending in "R" can be used only once. Discs ending in "RW" can be erased and rewritten.


Referral Whois. An experimental distributed whois service intended to replace the centralized Whois model. Work began in April 1995, with an active test bed of RWhois servers established between each of the regional registries in September 1995. The RWhois Operational Development Working Group is a forum for coordinating the deployment, engineering and operation of the RWhois protocol. User authentication will be required and operational procedures will be established. See InterNIC, DNS and Whois.


Receive. See TX/RX for detail.


Return to Zero. A method of transmitting binary information where voltage returns to a zero (reference) level after each encoded bit.

RZ Code

Return to zero code. A code form having two information states called "zero" and "one" in which the signal returns to a rest state during a portion of the bit period.

Newton[ap]s Telecom Dictionary
Newton[ap]s Telecom Dictionary
ISBN: 979387345
Year: 2004
Pages: 133

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