Caller ID Name CNAM
North America (US: database lookup; Canada: name carried in SIP signaling) · also called caller name, CNAM lookup
The name shown with an incoming call. In the traditional U.S. model the receiving carrier looks it up from a database keyed on the calling number; how the name is delivered varies by country and network.
CNAM (Caller ID Name) is the textual name shown alongside an incoming caller's number. How that name reaches your phone varies by country and network. In the traditional U.S. model the name is generally not sent with the call: the terminating carrier performs a CNAM database lookup on the calling number at call time and displays whatever name is on file. Other implementations carry the name in call signaling instead — notably in Canada, which has no national CNAM database, the display name is passed in SIP headers.
Where the name is looked up from a queried database rather than sent by the caller, CNAM data can be outdated, inconsistent between providers, or absent entirely.
Whether the caller "sends" their name depends on the network. In the traditional U.S. database-lookup model the receiving carrier supplies the name, so two phones can show different names — or none — for the same caller. Some networks (e.g. in Canada) do carry a name in signaling, so this is a common model, not a universal rule.