Ghost calls on the lines that cannot be explained or are some residual output of one Real-time Transport Protocol or RTP stream interacting with the PBX.
Ghost calls are generally caused by a neglected autodialer or indirectly as a consequence of restrictions applied to autodialers used for telemarketing by agencies such as the FCC that restrict how long they can tie up a phone line; the call is disconnected automatically at the calling end.
[1][2] Ghost calls can also be caused by accidental pocket dialing.
Several websites collect reports of ghost calls.
[citation needed] Repeated reports of the same number provide insight into where the machine is located and hopefully aid in having it shut down.