Yes, I tried to unplug jack from main control card after this happened but it made no difference. As soon as i plug back in, it starts ringing non stop. As far as any work or rewiring, no nothing done in years. The system is plugged in on UPS. The 4 incoming lines and 4 outgoing lines are connected to VOIPO Phone adapters for last 4 years.
There was an incoming call which got transfered to an extention and may be 2 seconds later it happened.