The service that we have come to know as "caller ID" is made up of two component services – the caller's ten-digit telephone number (CID) and the associated name (CNAM).
For any telephone call placed in the United States, the originating carrier is responsible for sending the caller's ten-digit telephone number (CID) to the recipient. The recipient's carrier is responsible for matching (if possible) a name record (CNAM) to the received telephone number from the global Line Information Database (LIDB). To put it briefly, CID is just the phone number, and CNAM is a global database with a name attached to that number.
Here is a real-world scenario to consider.
Casey's Bicycle Shop uses UpLync Communications as its telephone services provider. Casey often calls Zak's Bike Parts in San Francisco to order parts for his business. Zak's uses Comcast as its telephone services provider. When Casey dials Zak's, UpLync sends Casey's ten-digit telephone number to Comcast along with the call. Comcast tries to find a matching name to associate with Casey's telephone number (Casey's CNAM) before sending the call down the line to Zak's telephone. If the system works as it's supposed to, Zak's telephone displays Casey's ten-digit number and his business name when the call rings in.
For the scenario above to work correctly, several things have to happen.
- Casey's service provider, UpLync, must properly send Casey's ten-digit telephone number on all outbound calls.
- Casey's service provider must also have submitted Casey's business name to the global LIDB from which most national landline carriers perform CNAM lookups.
- Zak's service provider, Comcast, must have updated their internal CNAM records since UpLync submitted the new LIDB information.
- Zak's service provider must properly match the incoming ten-digit telephone number before sending the information along with the call to Zak's telephone.
Here are some common problems that prevent caller ID from working as desired:
- The originating service provider advertises the incorrect telephone number on outbound calls.
- The originating service provider hasn't submitted an updated CNAM record to the LIDB.
- The receiving service provider hasn't recently updated their CNAM records from the LIDB.
- The receiving service provider is failing to properly associate a name record with the incoming ten-digit telephone number.
Many mobile carriers don't use CNAM, so a cellphone will use its personal contacts as its only database. If your business number isn't in the cellphone's contacts, it won't find a name to associate with your incoming calls. In that situation, the phone carrier (AT&T, Verizon, etc.) manages labeling each individually from their internal databases