Q.850 cause 96 Mandatory information element is missing
Q.850 causeITU-T Q.850 Table 1
What it means
A field the protocol requires was missing from the message (Mandatory information element is missing).
Where you see it
In ISUP/BICC REL messages, 2G/3G DTAP Disconnect, and SIP Reason headers (Q.850;cause=…).
What to check
Report to whoever implements the sending node -- a protocol encoding issue.
Check the cause location (user, private or public network) to see which side released the call.
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