When an agent receives,an incoming call he hangsup/disconnect/ignore without answering. 

The call is clear at agent's end and he is ready for another call but the call is still active at caller/customer end.  I tried disconnecting the active call by "fsctl hupall normal_clearing" but failed, I also tried transfering call to to other extension in dialplan and hangup from there but no result.

Any help is appreciated.