SIP 180 Ringing
What SIP 180 means
Not an error. The destination is ringing. It is useful diagnostically because it proves the call reached a phone that is alerting, which rules out routing and registration entirely.
What SIP 180 Ringing actually means
The destination user agent has located the called party and is alerting them. Because it comes from the device that is actually ringing, it is positive proof that routing, registration and permission all worked.
What causes SIP 180 on a business phone system
- Normal call progressThe expected response when a phone starts ringing.
- Ringing with nobody answeringWhere callers report ringing forever, the call is reaching the phone and the issue is the no-answer handling rather than the connection.
How to fix SIP 180
- Use it to rule out whole categories of faultSeeing a 180 means routing, registration and barring are all fine, so an unanswered call is about ring timeouts and no-answer destinations.
- Set a no-answer destination if calls ring outSend unanswered calls to voicemail or a colleague rather than letting them ring indefinitely.
Fixing the underlying problem
This page explains the code. These guides walk through the fix in detail.
Questions about SIP 180
What does SIP 180 Ringing mean?
The phone you called is ringing. It is normal progress, and it is useful because it proves the call reached a device that is alerting, which rules out routing, registration and call barring as causes of whatever happens next.
Related SIP response codes
Source. SIP 180 Ringing is defined in RFC 3261 section 21.1.2 and registered in the IANA SIP Parameters — Response Codes. The causes and fixes above are drawn from our own experience supporting UK business phone systems.