I think it's Sip.

The kind of calls are called "Ghost Calls” and that happens when there are packets of data left in the telephone system. Those calls never come to our network as they are internal to you and your telephone system, However, your PBX technician should be able to rectify the issue very easily by either restricting the calls or send any calls with the matching call ID to an empty extension within the system and that way will never bother you again. Please let me know if there is any other question I can answer for you today.


Brian Kinney