440 4xx Client error RFC 5393
SIP 440 Max-Breadth Exceeded
The request could not fork further because of the Max-Breadth limit (protection against amplification).
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Common causes
- Excessive parallel forking, often from a misconfiguration.
How to fix it
- Reduce parallel forking or ring-group size.
Seeing 440 on calls through a router or firewall? Check that SIP ALG is disabled. It causes a surprising number of SIP errors. Read why.
About 4xx responses
The request has a problem or cannot be completed at this server, usually because of something on the requesting side or the target user.