I have an ISR 2811 serving as a voice gateway it has one E1 interface connecting to legacy PBX, i also have an a GSM gateway connected to it via FastEthernet, the gatway has 2 DSP with 16 channels both, total 32 channels. Last month i experienced very strange problem when i issue show isdn active i see many calls that are ended in reality but in isdn interface it show like they are still active maybe for days. One another issue i experienced is that when someone tried to call and lifts the phone up he automatically participate on one of the active calls and he listens all the conversation but on the other side the real callers do not know that someone is listening them. Really strange and complicated problem i hope that i was clear.
Thanx in advance