We are having an issue where we receive a call that rings all phones in our ring group with a 3CX phone system. When a user answers the call, no one is there. The call disconnects, then the next extension in the ring group will ring. The phones will continue to ring until every extension in the ring group answers the call.
There is no caller id showing on the phones, and no one on the other end of the call. Furthermore, the issue is reoccurring once every week to two weeks. It happens on a random day and time. We are not able to replicate the issue and is affecting clients that do not have a IVR.
We've open a ticket with our SIP provider and 3CX. Our SIP provider says that when this occurs, a SIP cancel is sent to the 3CX PBX but the PBX does not respond and the call gets caught up in the system. 3CX says it's a know issue with the phone system but has been over 2 months with no resolution. Any help would be appreciated.