D channel made busy (DMB) state, 270
data (D) channels
ISDN protocol and, 141–142
made busy state of, 270
data link layer, of OSI model, 305
data streams, VoIP calls and, 312–314
data transfer
evaluating need for services, 14–15
evaluating requirements for, 296
need for, 295
using frame relay networks, 300–304
using modems, 296–297
using MPLS, 304–307
using private lines, 297–299
dead air, troubleshooting, 225
decimal rounding
two versus four, 96
understanding, 97–98
dedicated carrier pricing, contract negotiations and, 17
dedicated circuits
activating individual channels, 203
analyzing phone lines needed for long-distance, 24
areas of responsibility for, 207
balancing, 266
checking monthly recurring charges for, 92
comparing calls over with switched calls, 216–218
confirming/denying problems with hardware on, 284–285
connecting hardware to carrier for activation, 202–203
cost of long-distance, versus switched phone system, 36–37
identifying circuit variables in DS-1 circuits, 262
identifying circuit variables in DS-3 or larger circuits, 261
identifying DS-0 or individual channel problems, 262–263
identifying levels of potential problems with, 260
introducing and reviewing conference call members for activation, 201–202
line coding and framing and, 136–137
local, 16
local loop options for, 149
local loop pricing and, 146–148
maintaining installation journal for toll-free, 200
making test calls on, 203
managing trouble tickets for, 271–272
ordering carrier-provided local loops, 150–152
ordering customer-provided local loops, 152–157
ordering without local loops, 157–160
out-of-band signaling and, 141–146
outpulse signal and start protocols and, 137–139
preparing for installation of, 160
preparing for installation of toll-free, 198–200
preparing technical cut sheet for, 161–164
problems with, local loop and, 216
recommended participants of installation of toll-free, 194–196
requesting hot cut or parallel cut on, 194
testing toll-free numbers on new, 204–205
time division multiplexing and, 134–136
toll-free numbers and, 66–67
trunk groups and, 139
understanding call quality issues with, 263–265
understanding circuit failure, 265–266
understanding configuration of, 134
understanding costs of long-distance, 35–36
understanding installation fees for, 92
versus switched service, 15–17
dedicated service
building specific issues for, 60
necessary equipment for, 57–59
overview, 55
terminology of, 56
dedicated toll-free numbers. See also toll-free numbers
checking by redialing, 288–289
handling quality problems, 292
head-to-head testing, 291
identifying provisioning problems with, 287–288
negotiating hot cut without RespOrg, 191–192
ordering, 179–183
resolving activation without hot cut, 187–189
resolving cancellation before activation problem, 189–191
troubleshooting, 287
using hot cut to activate, 183–185
validating DNIS configuration four, 290–291
validating RespOrg, 289–290
versus switched, 165
default settings, hardware restoring to, 273
demarcation point (demarc)
inside wiring responsibility and, 62
looping CFA point and, 283–284
D4/SF, 137
dial tones
eliminating reorigination of, 38
with key system, 29
dial-around codes
avoiding problems with, 130
benefits of using, 128–129
forcing long-distance carrier use with, 127
functioning of, 239
no-PIC designation and, 129
troubleshooting with, 238–240, 241–243
understanding, 127–128
Dialed Number Identification Service (DNIS)
ordering toll-free numbers and, 180–181
toll-free service and, 80–81
understanding, 182
validating configuration, 290–291
Dialogic cards, synch problems caused by, 275
Direct-Inward Dialing (DID) service, dedicated long-distance circuits and, 16
disclaimer, CFA, 155
discounts, reviewing on invoice, 94
DLR (Design Layout Record), understanding for customer-provided local loops, 155–156
DMB (D channel made busy) state, 270
dropped calls, troubleshooting, 226
DS-1 circuit
identifying circuit variables and, 262
identifying problems with, 260
overview, 56
DS-3 circuit
identifying circuit variables in, 261
identifying problems with, 260
overview, 56
DS-0 circuit
identifying problems with, 260, 262–263
overview, 56
duplicate calls, checking for, 104–105