What is Caller ID ?
Caller ID is a Telco offering that is a byproduct of (C)LASS services. In this case, only those numbers reported by participating exchanges are returned, exactly which are and which are not is currently (March 1994) at the Telco's discretion.
The Federal Government has stated that it is their intent that nationwide CNID be available by mid-1995. The full text of this decision may be found FCC Report No. DC-2571 issued on March 8, 1994.
The biggest effect of the ruling is to mandate transport of CPN (customer provided number) information between interconnecting networks eliminating the effective inter-LATA-only limitation that exists today in most areas.
Currently there are two types of Caller ID. The first (often referred to as "basic" service) returns just the calling number or an error message and the date/time of the call.
The second ("enhanced" Caller ID) also may return the directory information about the calling number. At a minimum, the name of the subscriber is returned (the subscriber is not the same as the caller, the phone company has no way to determine who is actually on the line).