Calling Name Identification (CNAM)

Calling Name Identification (CNAM)

First, a little background on CNAM:
  1. The line information database (LIDB) is a collection of commercial databases used in the United States and Canada by telephone companies to store and retrieve Calling Name Presentation (CNAM) data used for caller ID service.
  2. The databases map telephone numbers to 15-character strings of caller names. Class 5 telephone switches, which provide end-office services in exchange areas, query the National LIDB database to procure the information for numbers that do not belong to them.
  3. In the USA, caller ID name information is not transmitted from the originating office to the destination office. It is the terminating carrier that is responsible for providing the caller ID information to its customers. The carrier performs a database lookup using the caller's telephone number to obtain the name information for the caller ID service.
  4. Per carrier policy, the name of a person or business may be automatically added to the Line Information Database and the customer must opt-out to remain anonymous. Other carriers exclude identity information by rule, and require the subscriber to opt-in. If the identity information is not available, then the maintainer of the database often returns geographic information, such as the city and state. In case of a failure, the maintainer of the database may also return "NOT AVAILABLE".
  5. The CNAM databases are independent databases operated by LECs and other private companies. The called party's carrier has the responsibility to perform the CNAM lookup, and it is possible that lookups for the same telephone number from different locations return different name information.

What 46 Labs can do is enter the number and CNAM into the LIDB database.  If there are numbers they are dialing from that have not been entered into the LIDB database or the information entered was wrong, we can assist.  Beyond that, it is the terminating carrier’s responsibility to dip the database and insert CNAM.  This is outside of our control and how a terminating carrier handles CNAM differs unfortunately. 

Examples: 
  1. Some carriers don’t even dip the call at all (they’re trying to avoid expense).
  2. Some cache CNAM information instead of dipping calls real-time (where there is the potential for an old LIDB entry to be displayed).  Again, this is so the carrier avoids expense.
  3. Even if a carrier upstream (who does not have responsibility to dip the call) dips and inserts CNAM, the terminating carriers may strip what is in the field and follow their own process.  There used to be apps where you could insert things in the CNAM field where people would play jokes or attempt something nefarious, thus carriers stripping the information.
  4. The ones that do things effectively dip every call they’re terminating to their end users to display what is currently in the LIDB database.
  5. For a carrier to change how they’re handling CNAM, an end user of the carrier would need to open a ticket with their underlying service provider (example would be a T-Mobile customer opening a ticket with T-Mobile).  Carriers are not usually responsive to CNAM complaints from parties that are not their customers of record.
  6. Some mobile carriers are technologically incapable of sending CNAM with all their calls and in some cases it is limited by the actual mobile phone being used by their customer.
  7. There are no regulatory requirements on carriers to provide this service to their customers.

Long story short, CNAM is considered a “service” to the customers receiving calls and not the customers placing calls.  Terminating carriers do not deliver this service to their customers in a uniform fashion.

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