o each carrier for billing and call-routing purposes. AT&T's CIC is 0288. If someone at a pay telephone dials 1010288 and then the telephone number she is calling, the call is routed over the AT&T network. CIR (Committed Information Rate) A term used in frame relay MPLS networks to indicate the speed of the transmission guaranteed for a customer. See also MPLS. circuit switching The establishment-by dialing-of a temporary physical circuit (path) between points. The circuit is terminated when either end of the connection sends a disconnect signal by hanging up. CLEC (Competitive Local Exchange Carrier) www.TechnicalPDF.com A competitor to incumbent local telephone companies that has been granted permission by the state regulatory commission to offer local telephone service. CLECs compete with the incumbent telephone company. CLECs are also simply called local telephone companies. CLID (Calling Line ID) The number that identifies the telephone number from which a call was placed. For most residential customers, the calling line ID is the same as their billing number, their Automatic Number Identification (ANI). CO (Central Office) The location that houses the telephone company switch that routes telephone calls. End offices are central offices that connect end users to the Public Switched Telephone Network. compression The reduction in size of data, image, voice, or video files. This decreases the capacity needed to transmit files. concatenation The linking of channels in optical networks SO that voice or video is transmitted as one stream. This is done to ensure that there are no breaks in the transmission. connectionless service The Internet protocol is connectionless. Each packet travels through the network separately. If there is congestion, packets are dropped. Packets are reassembled at their destination. contact center Another term for automatic call distribution. The term contact center implies that call centers have the capability to respond to e-mail and facsimile as well as voice calls. containers www.Te