Caller ID and CNAM

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“Caller ID”, as it is most commonly thought of, actually consists of two different services working together to display both the phone number and name of the caller for phone calls. 

What is the difference between Caller ID and CNAM?
Caller ID (aka “CLID”) is the actual phone number calling in, whereas the accompanying text that provides the identifying name for that number is referred to as CNAM (aka “Caller Name”). 

How do CLID and CNAM work together?
When a phone call is made, the CLID is routed to the destination’s carrier for delivery. The CNAM text data is not sent out by the originating carrier, as they are separate services. 

When the call arrives, the carrier for this destination end of the call will reference that number against its own local CNAM database. At this point, both a CLID number and CNAM text delivered to the recipient’s phone when it rings through. 

What is a CNAM Database?
CNAM databases (aka “Line Information Databases”) are official, authoritative sources where the CNAM text data is recorded for any given phone number. There are multiple CNAM database providers that maintain these centralized records, and carriers may subscribe to one or several of them. 

What are the limitations of CNAM?
  • The number must be a local number; toll free numbers are not supported. 
  • Maximum of 15 characters for the text string. 
  • For highest compatibility, do not include any special characters.
  • As CNAM transmission is the responsibility of the terminating carrier, that terminating carrier must support CNAM functionality and have up to date records. 
Why is my number not consistently showing an accurate CNAM?
When RingCentral updates the CNAM for your number, it is submitted to the centralized CNAM database. When the recipient receives a call, their carrier references its own local CNAM repository that may or may not be up to date.  

In order for the CNAM to be displayed accurately, the terminating carrier to whom the calls are getting delivered to must have updated their local repository from the official database(s). This update is referred to as a “dip”. Depending on the carrier, they may not perform these dips regularly, thus the recipient may be seeing outdated information for your number. Usually large carriers keep up to date with these centralized databases regularly; you are more likely to notice a problem when a smaller carrier is involved. 

RingCentral provides support for local, main company number CNAM changes, and we are responsible for ensuring that the proper databases are updated in a timely fashion. However, we cannot take responsibility for how a third party provider manages their own repositories, nor force them to update their records. 

If you are noticing that some of your callees are receiving outdated CNAM information for your number, please notify us so that we may verify that the CNAM databases were updated correctly on our end. If the CNAM database was updated by RingCentral, your callee will then need to contact their carrier as well to make sure its records are up to date going forward.
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Kim, Alum

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Posted 2 years ago

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