PBX (Private Branch eXchange)

PBX generations 0–3 were all circuit switches, optimized for voice. It wasn’t until the 1980s that the third generation of PBXs supported data communications, and even then on a circuit-switched basis through special, and very expensive, data modules. The primary physical and logical components of a 3rd-generation PBX include power supply, common control, memory, switching matrix, trunk interfaces, line interfaces, and terminal equipment, as illustrated in Figure P-1.

Line

• CIC (Carrier Identification Code)
• CIC (Carrier Identification Code)
• CIDR (Classless Inter-Domain Routing)
• CIDR (Classless Inter-Domain Routing)
• CIF (Common Intermediate Format)
• CI II (Computer Inquiry II)
• CIP (Classical IP over ATM)
• cipher
• CIR (Committed Information Rate)
• circuit
• circuit switch
• circuit-switched data (CSD)
• circuit-switched network
• circuit terminating equipment
• Citizens Band (CB)
• cladding
• Clarke orbit
• Clarke, Sir Arthur C. (1917–)
• Class 1
• Class 1
• Class 2
• Class 2
• Class 3
• Class 4
• Class 4/5