423 4xx Client error RFC 3261
SIP 423 Interval Too Brief
The registration expiry is shorter than the registrar allows. The response includes Min-Expires.
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Common causes
- Phone set to re-register too often (for example, every 30 seconds).
How to fix it
- Raise the registration expiry to at least Min-Expires. Use NAT keep-alives (OPTIONS or CRLF) instead of very short registrations.
Seeing 423 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.