SIP 302 Moved Temporarily
Retry at the address in Contact for now. Common for call forwarding.
3xx Redirection · RFC 3261 · Answer to OPTIONS: Up. It answered with a redirect.
What SIP 302 means
A 302 says the request should be retried at a different address, given in the response's Contact header. The redirect is temporary: the caller uses the new address for this attempt, and an expires parameter may say how long the redirect stays valid. Many systems use it to forward calls without staying in the call themselves.
The server that sends a 302 steps out of the call. Whoever receives it, the caller or a proxy on the way, decides whether to follow the redirect by sending a new INVITE to the Contact. If nobody follows it, the 302 becomes the final answer and the call fails, even though the redirect itself did its job.
Example response
SIP/2.0 302 Moved Temporarily
Via: SIP/2.0/UDP 198.51.100.14:5060;branch=z9hG4bK-302-f6
From: <sip:+[email protected]>;tag=e3d1
To: <sip:+[email protected]>;tag=rd-0b2
Call-ID: [email protected]
CSeq: 7 INVITE
Contact: <sip:+[email protected]>;expires=3600
Content-Length: 0Common causes of SIP 302
- Call forwarding is set on the number, and the PBX redirects the call instead of forwarding it itself.
- A redirect server or load balancer points callers at the node that should take the call.
- A number moved to another platform, and the old platform redirects to the new address.
- The carrier or SBC doesn't follow redirects, so the 302 reaches the caller as a failed call.
- The Contact points to an address the caller can't reach or isn't allowed to call, so the retry fails.
How to fix SIP 302
- Read the Contact header: it is the address the call should have gone to next.
- Check whether your SBC or carrier acts on 3xx responses; if it doesn't, enable it or have the PBX forward the call itself.
- Try the Contact address directly to see whether the redirect target is the real problem.
- Look for redirect loops, where two systems send the call back and forth until a hop or time limit ends it.
SIP 302 as an answer to OPTIONS
A 302 to OPTIONS means the server is up and points you somewhere else. PingVo doesn't follow the redirect: it records the 302 as the answer, and a PingVo Route counts it as reachable by default. If the Contact names a different SBC, that may be the address your Route should probe instead.
Questions about SIP 302
What is the difference between SIP 301 and 302?
301 says the user has moved for good, so callers may update their records. 302 is temporary: use the new address for now, but keep the original for later calls.
Why does a 302 end my call?
Nothing on the path followed the redirect. The server that sent it did its part; the caller or the next proxy has to send a new INVITE to the Contact.
Is a 302 to INVITE acknowledged?
Yes. Like any final response to an INVITE that isn't a 2xx, it is acknowledged hop by hop before the caller tries the new address.