Why is the Caller ID Being Sent Twice?

While Caller IDs are sent once by SIP carriers, in some cases, it can be sent twice. When the caller ID is sent more than once, this is a symptom of a larger issue which is usually found on the SIP carrier's side from their primary registration server blacklisting the phone system's IP. 

How to Fix It

To correct this issue, reach out to your SIP Carrier and have them whitelist the phone system's IP. Once the IP has been removed from their blacklist, the caller ID will be sent over once from the SIP Carrier.