Caller ID

Caller ID is the information presented with a telephone call to identify its apparent origin. It usually includes a calling number and may also include a name, depending on the network, device and directory services involved. The information travels through signalling systems and is interpreted by the receiving network before it appears on a recipient's screen.

A displayed number is not, by itself, proof of the caller's identity or authority. Networks may modify presentation information, and caller identity can be misrepresented through spoofing. Identity authentication mechanisms and directory lookups address different parts of that problem; neither should be confused with whether a recipient wants the call. For business calling, the presented number should be appropriate for the call and usable for return contact where applicable. When troubleshooting, record what the recipient actually sees rather than assuming it matches the number selected by the originating system. Local rules can also affect which identities may be presented.