log 2 %CALL_CONTROL-6-CALL_LOOP: The incoming call has a global identfier already present in the list of currently handled calls. It is being refused
This message informs you that the AS5400 has received an incoming voip call generated from itself. In a SIP scenario the unique global identifier is the SIP CALL-ID. When the AS5400 creates a new voip call leg, generates a new and unique CALL-ID. If it receive a call with the same CALL-ID it's a loop. The loop must be block.
Try to identify and eliminate the loop cause.
Check your telephony routing, dial-peers configuration, hunting and huntstop, decrease max forward numbers, etc.