Caller ID

Caller ID (caller identification, CID), also called calling line identification (CLID), calling number delivery (CND), calling number identification (CNID) or calling line identification presentation (CLIP), is a telephone service, available in analog and digital phone systems and most voice over Internet Protocol (VoIP) applications, that transmits a caller's number to the called party's telephone equipment during the ringing signal, or when the call is being set up but before the call is answered. Where available, Caller ID can also provide a name associated with the calling telephone number. This service is called CNAM. The information made available to the called party may be displayed on a telephone's display, on a separately attached device, or personal computer.