Phone ID, commonly known as Caller ID, works by transmitting information about the calling party to the receiving party before the call is answered. While the term "Caller ID" is widely used, it encompasses two separate but related services: Caller ID and Caller Name Delivery (CNAM).
Caller ID (Calling Number Delivery)
Caller ID, in its most basic form, transmits the calling party's phone number. This number is sent electronically between telephone switches after the call is initiated but before it is answered. The receiving phone or device then displays this number.
CNAM (Caller Name Delivery)
CNAM provides the name associated with the calling number. This service relies on databases maintained by telephone companies and third-party providers. Here's how it generally works:
- Call Initiation: When a call is placed, the phone company originating the call queries a CNAM database.
- Database Lookup: The database is searched using the calling party's phone number.
- Name Retrieval: If a matching name is found, it's transmitted along with the phone number.
- Display: The receiving phone displays both the number and name (if available).
Important Considerations:
- Database Accuracy: CNAM databases are not always accurate or up-to-date. This is why you sometimes see outdated or incorrect names displayed.
- Privacy: Callers can block their phone number (and name) from being displayed using specific codes (e.g., *67 in the US). This prevents the Caller ID/CNAM information from being transmitted.
- CNAM limitations: CNAM lookups can sometimes fail depending on the region, phone provider or specific settings. If a caller's name isn't found in a database, the receiving phone may only display the phone number or "Unknown Name".
- SPIT (Spam over Internet Telephony): Phone ID can be spoofed, meaning the number and name displayed are not the actual caller’s identity. This is commonly used in spam and scam calls.
In short, phone ID relies on the transmission of the calling number and, through CNAM databases, the calling name. However, the accuracy and availability of the name depend on the database quality and privacy settings of the caller.
