SIP 487 Request Terminated
The request was cancelled by a CANCEL or BYE before it completed.
4xx Client failure · RFC 3261 · Answer to OPTIONS: Up. It rejected the request.
What SIP 487 means
A 487 is the final response to an INVITE that was cancelled before it completed. The caller, or a proxy acting for it, sent CANCEL while the call was still ringing, and the far end closes the INVITE transaction with 487. The 200 to the CANCEL and the 487 to the INVITE are two separate responses, and the caller still acknowledges the 487.
Most 487s are not faults. They are callers hanging up during ringing, or the losing branches of a forked call: when one device answers, the proxy cancels the others, and each of them answers 487. A high rate of 487 points at long ringing or short timers, not at a broken trunk.
Example response
SIP/2.0 487 Request Terminated
Via: SIP/2.0/UDP 198.51.100.28:5060;branch=z9hG4bK-487-v1
From: <sip:+[email protected]>;tag=b8c4
To: <sip:+[email protected]>;tag=rt-15
Call-ID: [email protected]
CSeq: 8 INVITE
Content-Length: 0Common causes of SIP 487
- The caller hung up while the call was still ringing.
- The call was forked to several devices, one answered, and the proxy cancelled the rest.
- A no-answer timer on the PBX, the SBC or the carrier ran out and sent CANCEL.
- An IVR or test system ended the attempt on purpose after a fixed ringing time.
How to fix SIP 487
- Look at how long calls rang before the CANCEL; if it is always the same, a timer sent it, not a person.
- Find which system sent the CANCEL, and compare its no-answer timer with the time callers need to reach an agent.
- In call statistics, count 487s from forked branches separately; they aren't failed calls.
- If callers abandon during long ringing, shorten the time to answer, for example by answering into a queue sooner.
SIP 487 as an answer to OPTIONS
A 487 answers a cancelled INVITE, and an OPTIONS probe is never cancelled, so it isn't an answer a healthy server should send to one. If it arrives anyway, it still proves the server is processing SIP, and a PingVo Route counts it as reachable by default.
Questions about SIP 487
Is SIP 487 an error?
Usually not. It is the normal end of a call that was cancelled during ringing, either by the caller or by a proxy after another device answered.
Why do I see 487 after a CANCEL I didn't send?
Another system on the path sent it, usually because its no-answer timer expired first. Compare the timers on each hop to find the one that gives up earliest.