SIP 482 Loop Detected

What SIP 482 means

A server spotted that it had already handled this call and stopped it going round again. Like a 483 it means there is a routing loop, but here the loop was caught by a server recognising its own fingerprint rather than by a counter running out.

Client error (4xx)
Sent by A server that recognised itself in the path
Rare

What SIP 482 Loop Detected actually means

The server detected a loop by finding itself in the request path. It is the more precise of the two loop protections, because the server knows for certain the request has passed through it before rather than inferring it from an exhausted counter.

What causes SIP 482 on a business phone system

A routing rule sends calls back through the same serverTypically a route pointing at a destination that resolves back to the origin, which is easy to create when chaining systems together.
Two systems forward to each otherThe same underlying mistake as a 483, caught differently.

How to fix SIP 482

Trace the route the call takesFollow each hop and find where it returns to a system already in the path.
Terminate chains at voicemail or an announcementEnding every branch somewhere final makes loops structurally impossible.

Fixing the underlying problem

This page explains the code. These guides walk through the fix in detail.

Changing call routing and ring groups

Questions about SIP 482

What is the difference between SIP 482 and SIP 483?

Both mean a loop, caught by different mechanisms. A 482 is a server recognising itself in the call path, so it knows there is a loop. A 483 is a hop counter reaching zero, which infers one. The fix is identical: find the two destinations pointing at each other.

Related SIP response codes

Source. SIP 482 Loop Detected is defined in RFC 3261 section 21.4.20 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.

All VoIP & SIP codes