ital hierarchies, 125f information capacity, binary system, 31 international link synchronization, 141-142 information channels, 78 international Morse code, 22 multiplexing methods for, 79 international signaling networks, 374-375 information field international signaling point (ISP), 375 frame relay frame structure, 331-332 international signaling point code (ISPC) HDLC frame format, 287 numbering plan, 377-378 information frame, HDLC, 286 International Standards Organization (ISO), information local switch function, 70 278-279, 280 infrastructure mode, 342 international switching center (ISC), 176, 178, 181 ingress noise, CATV system, 451 internet, data communications for, 251 inheritance tree, 563 internet control message protocol (ICMP), 324 initial address message (IAM), 382, 383f, 384 internet datagram, 325. See also datagram routing inlets, 59, 67 method input/output (I/O) device, 2-3 internet protocol (IP), 319. See also IP entries; insertion gain, 630-631 transmission control protocol/internet protocol insertion loss, 443, 630-631 (TCP/IP) hybrid device, 77 internetworking equipment, in troubleshooting, 543 Institute of Electrical and Electronic Engineers interoffice signaling, 361 (IEEE), 802 series specifications, 15. See also interregister signaling, 150, 154, 155 IEEE entries intersymbol interference (ISI), 214, 233, 234, 268, insulators, 33, 575 272, 465, 476 integrated access device (IAD), 391 intraframe coding techniques, 419 intelligence intranets, 292 conveying over the telegraph, 22-23 invalid frames, 332 signal conveyance of, 19 inverted sideband, 81 intelligible crosstalk, 50 IP connectivity, 357. See also internet protocol (IP) INTELSAT digital link parameters, 229 IP layer, 325 FDMA and TDMA with, 221 IP packets, 389, 393f INTELSAT standard, 220 used for VoIP, 392 INTELSAT VIII satellites, 220 IP routing algorithm, 322-324 interconnection local switch function, 70 ISDN (Integrated Services Digital Network[s]), 13, interexchange carrier network, 176 251, 327-328 interexchange carriers (IXCs