An interworking issue occurred with another network/technology, unspecified.
Where you see it
In ISUP/BICC REL messages, 2G/3G DTAP Disconnect, and SIP Reason headers (Q.850;cause=…).
What to check
Check the interworking point (e.g. SS7-to-SIP gateway) between the two networks/technologies.
Check the cause location (user, private or public network) to see which side released the call.
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