ISDN (Integrated Services Digital Network)

• Main Features:
  • All-digital telephony system

  • Integrated services for ordinary data, voice, and sometimes video (e.g., in videoconference)

• B (Bearer) channel: 64 kbps for data
  • Mostly circuit switched, but also supports packet switching

  D (Delta) channel: 16 kbps

  • D-channel takes care of call set-up, call control (call forwarding, call waiting, etc.), and maintenance

  • Control and maintenance can be done in real-time in D-channel while B-channel is still transmitting data

• Basic Rate: two B-channel and one D-channel

  Primary Rate: 23 B-channels and one D-channel in U.S. and Japan; 30 B-channels and two D-channels in Europe

• Broadband ISDN (B-ISDN)
  • Add H-channels whose bandwidth ranges from 384 kbps to over 130 Mbps per channel (see Table 10.3, p. 372 of Steinmetz and Nahrstedt)

  • Since 1988, ATM is the basis of B-ISDN