SIP 484 Address Incomplete
The Request-URI is incomplete, for example a partially dialled number.
4xx Client failure · RFC 3261 · Answer to OPTIONS: Up. It doesn't recognise the address we asked for.
What SIP 484 means
A 484 says the Request-URI is incomplete: the server recognised the start of the address but needs more to route it. On a trunk this usually means the number has too few digits for the dial plan, or lacks the country or area code the carrier expects.
The code comes from overlap dialling, where a phone sends digits as they are pressed and the network asks for more. Most SIP trunks expect the whole number in one INVITE, so a 484 today is usually a formatting problem. RFC 3398 maps Q.850 cause 28, invalid number format, to 484.
Example response
SIP/2.0 484 Address Incomplete
Via: SIP/2.0/UDP 198.51.100.26:5060;branch=z9hG4bK-484-t8
From: <sip:+[email protected]>;tag=1c7e
To: <sip:[email protected]>;tag=ai-3e
Call-ID: [email protected]
CSeq: 6 INVITE
Reason: Q.850;cause=28;text="Invalid number format (address incomplete)"
Content-Length: 0Common causes of SIP 484
- The number was sent without the country or area code the carrier needs.
- A dial plan rule stripped too many digits before sending the call to the trunk.
- The caller dialled a short code or an extension that the trunk can't route.
- The PBX started the call before the user finished dialling, so the INVITE carried a partial number.
- The phone network reported an invalid number format, which a gateway maps to 484.
How to fix SIP 484
- Compare the number in the Request-URI with the full format the carrier documents, usually E.164 with a plus sign.
- Walk through the PBX dial plan rules that touch the number and check what each one adds or removes.
- Increase the inter-digit timeout on phones that send calls before dialling is complete.
- Test the same number in full international format; if that works, the fix is a normalisation rule.
SIP 484 as an answer to OPTIONS
A 484 to OPTIONS means the server is up but doesn't recognise the address the probe asked for. It treats the Request-URI as a partial address, which can happen when an SBC expects a number and the probe names only a host. A PingVo Route counts it as reachable by default.
Questions about SIP 484
What is the difference between SIP 484 and 404?
404 says the address doesn't exist. 484 says it might, but the number is incomplete, so adding digits or a prefix can fix it.
Do SIP trunks still use overlap dialling?
Rarely. Most send the complete number in the first INVITE, so a 484 usually means the number is missing digits.