ANI

ANI is a service that provides the telephone number of an incoming call. ANI is used for a variety of functions, such as:

• Telephone companies can direct a call to the proper long-distance carrier's equipment (based on the originating, or sending ANI)

• Help identify the caller's address for 911 calls

• Route 800# calls to the nearest vendor

• Call centers to identify the calling party to better service a customer

ANIs are constructed per the NANP. The NANP was designed to allow for quick and discreet connection to any phone in North America. The NANP is comprised of three elements:

• Area Code (NPA)

• Exchange CO Code (Nxx)

• Station Subscriber Number (xxxx)

Each of these is discussed in the following sections.

Area Code (NPA)

The Area Code, or Numbering Plan Assignment (NPA), identifies the calling destinations area. The first number of an NPA is 2-9, with 0 and 1 reserved. Zero (0) is reserved for operator access or operator services; One (1) is reserved for the local switching office to immediately set up a tandem switch connection for a long-distance toll call.

Certain NPAs have been set up for predefined or specific functions. These are:

• 456 Nxx

• 900/976 Nxx

• 500 Nxx

• 8xx (800/888/877/866/855)

456 NXX

Numbers within the 456 NPA are used to identify carrier-specific services. Carrier identification is provided within the dialed digits of the E.164 number; the prefix following 456 (456-NXX) identifies the carrier. Use of these numbers enables the proper routing of inbound international calls destined for these services into and between NANP area countries.

Current 456-NXX assignments are provided in Table 17-1:

Table 17-1. 456-NXX Assignments

NXX	CARRIER
226	Teleglobe Canada
288	AT&T
289	AT&T
333	Startec, Inc.
624	MCI
640	Sprint
741	STSJ
808	Hawaiian Tel

900/976 Nxx

900 numbers are used to identify premium services, and the cost of calls to these services is billed to the calling party.

900 numbers are in the format of 900-NXX-XXXX. 900 service is not portable; the identity of the service provider is embedded in the number. The prefix (NXX) indicates the 900 service provider, and the line number (XXXX) indicates the particular premium service.

NOTE

When talking about telephone numbers "portable" means that the customer owns the number and can move the number to different carriers. When a number is not portable it means the carrier owns the number, not the customer.

500 Nxx

500 numbers are used for "follow me" personal communication services.

500 numbers are in the format 500-NXX-XXXX. 500 service is not portable; the identity of the service provider is embedded in the number. The prefix (NXX) indicates the 500 service provider, and the line number (XXXX) indicates the particular premium service.

8xx (800/888/877/866/855) Toll-Free Numbers

8xx toll-free is an automatic reverse-charge service. Instead of the caller paying for the cost of the call, it is automatically charged to the called number (the receiver). This includes surcharges, such as the payphone surcharge and toll-free directory assistance.

NOTE

Toll-free service in the U.S. is called Free-Phone in the rest of the world (ROW).

Toll-free numbers are commonly used by businesses so that their customers do not have to pay to call them. This free service is especially important today as more and more businesses are centralizing their support operations and are using interactive voice response (voice menu prompts) services.

Many non-business consumers have also found the toll-free numbers useful. These users will give the toll-free number to their family members so that when they are away from home, they can call without paying exceptionally high payphone, hotel, motel, and hospital rates.

Toll-free numbers have an associated "ring-to" (termination) number. This is commonly the main business telephone number or the primary telephone number at a residence. When someone calls the toll-free number, the telephone network looks up the toll-free number to find the carrier that handles the call and the ring-to number associated with the toll-free number and routes the call to the carrier for delivery.

Exchange CO Code (NXX)

This is the CO designator designator that lists the possible number of central office codes within each area code (NPA).

Certain NXXs have been set up for predefined or specific functions. These are:

• 555-xxxx

• 800-855-xxxx

• 555-Numbers (555-xxxx)

555 numbers are used to reach a wide variety of information services are reached by 555 numbers. For example, NPA-555-1212 will provide directory assistance information for the specified NPA.

555 numbers are in the format 555-XXXX, where the line number (XXXX) indicates the particular information service. The ATIS-sponsored Industry Numbering Committee assigns 555 numbers.

555 numbers may be assigned for either national or local use. A national assignment requires that the 555 number be implemented in at least 30 percent of all NPAs or states or provinces in the NANP Area. A local assignment is made for implementation in certain NPAs specified at assignment time.

800-855 numbers, in the format 800-855-XXXX, are used to access Public Switched Telephone Network services intended for use by the deaf, hard of hearing, or speech impaired. Such services include Telecommunications Relay Service and Message Relay Service.

Station Subscriber Number(XXXX)

This number identifies the service subscriber of the CO identified by the Nxx. There are no special or reserved XXXX numbers.