press-to-talk (PTT)

channel for signaling and control, and is backward-compatible with E-1 transmission. Primary rate interface (PRI), the North American version, offers 23 bearer (B) channels, plus one data (D) channel, and is backward-compatible with T1 and J-1 transmission systems. PRI and PRA both provide a full-duplex (FDX) point-to-point connection through an NT2-type intelligent CPE switching device, such as a PBX

or router, for interfacing with the central office (CO) switch.The B and D channels are clear channels of 64 kbps, as signaling and control are out-of-band.The B channels can be used individually to connect on demand to any other ISDN device, or multiple B channels can be bonded and treated as a single fast connection for bandwidth-intensive applications such as data file transfers, videoconferencing, and any multimedia combination. Although the D channel is reserved exclusively for signaling and control, those functions are fairly light. ISDN standards, therefore, provide for non-facility associated signaling (NFAS), which allows a D channel to support up to five PRA/PRI circuits. See also B channel, bond, BRI, CO, CPE, D channel, E-1, FDX, ISDN, J-1, out-of-band, PBX, PRI, router, signaling and control, and T1.

• continuous redial
• contraction
• Controlling the Assault of Non-Solicited Pornography and Marketing Act (CAN-SPAM Act)
• control plane
• control unit
• conventional band (C-Band)
• convergence
• Convergence Sublayer (CS)
• converter box
• .coop (cooperative)
• coordinated dialing plan
• copper (Cu)
• Copper Distributed Data Interface (CDDI)
• copyright (©)
• cordboard
• cordless telephone
• Cordless Telephony generation 0 (CT0)
• Cordless Telephony generation 1 (CT1)
• Cordless Telephony generation 1 plus (CT1+)
• Cordless Telephony generation 2 (CT2)
• Cordless Telephony generation 2 plus (CT2+)
• Cordless Telephony generation 3 (CT3)
• core
• core
• core switch