SIP 484 Address Incomplete: what it means and how to fix it
Short answer: SIP 484 Address Incomplete means the number sent in the Request-URI is incomplete and the destination cannot complete the call without more digits. The most common cause is a PBX dialing rule that cuts digits, such as the area code (DDD), the ninth digit of a mobile number or part of an 0800 number. Compare the number sent with the full expected format.
| Code | 484 |
|---|---|
| Official name | Address Incomplete |
| Class | 4xx: request failure |
| Defined in | RFC 3261 |
| Q.850 causes that usually come with it | 28 (Invalid number format (address incomplete)) |
How Monitor treats SIP 484
The reading depends on what should answer the number, which is the question 2N5 answers when it adds each circuit. These are the rules the product applies today, generated from the same function that judges every test call.
| What should answer the number | Reading |
|---|---|
| A greeting or recorded message (the IVR) | Down |
| A test tone or echo service | Down |
| Other: it may ring or be answered | Down |
What Monitor records for an IVR: The provider refused the call: the number dialed is incomplete (SIP 484).
A call read as Down alerts nobody on its own: it is repeated 3 times, every 2 minutes, and only 4 failures in a row open an incident, with each call's SIP code and Q.850 cause as evidence for the carrier. At the default pace, every circuit is tested every 15 minutes.
If the carrier returns SIP 484 when 2N5's calling account registers, before any call, the test is monitoring blind: it is a problem on 2N5's side, it does not count against the circuit and it does not alert the customer.
What does SIP 484 mean in practice?
Under RFC 3261, SIP 484 Address Incomplete indicates that the server received a request with an incomplete Request-URI. The RFC recommends that the reason phrase carry more information. The code is also used in overlap dialing (RFC 3578), where the number is sent a few digits at a time and the 484 asks for more digits.
On SIP trunks in Brazil, overlap dialing is rare, and a 484 almost always means the PBX sent fewer digits than it should have. Formats vary: a local call with 8 digits (landline) or 9 (mobile), long distance with 0 + carrier selection code (CSP) + area code (DDD) + number, 0800 numbers with 11 digits, or E.164 with +55. A rule that strips the wrong prefix produces the SIP 484 error. If the number is complete but does not exist, the expected code is SIP 404.
Common causes in Brazil
- An outbound rule in FreePBX, Issabel or 3CX that strips too many digits, for example removing the area code along with the
0. - A mobile number dialed without the ninth digit, still present in old phone books and records.
- An 0800 number saved with one digit missing in the IVR, the CRM or the PBX.
- An IP phone with a dial plan that sends the number too early, before the user finishes keying it in.
- A long-distance number sent without an area code to a carrier that requires the area code on every call.
- A short service number that the carrier does not recognize in that form.
How to diagnose it
- Capture with
sngrep port 5060and count the digits in the Request-URI of the INVITE that got the 484. - On Asterisk or FreePBX, turn on
pjsip set logger on(orsip set debug onwith chan_sip) and compare the number dialed on the extension with the number that went out to the trunk. - Review the outbound routes (dial patterns, prefixes to strip and to add) in FreePBX or Issabel. On 3CX, review the outbound rules and enable “Verbose logging.”
- On Asterisk, use
dialplan show <number>@<context>to see which rule matched the number. - Test the same destination in the full format, for example area code plus number, and in E.164, to find out what the carrier accepts.
- Check for the
Reason: Q.850;cause=28header (RFC 6432) in the response, if the carrier sends it.
What to send the carrier
- Date and time of the attempts, with the time zone.
- Calling number (A) and called number (B), exactly as they appeared in the Request-URI.
- The Call-ID of at least one call.
- The full 484 line and the Reason header with the Q.850 cause, if present.
- The dialing format you are using and how many attempts failed.
- The pcap of the capture, when available.
Frequently asked questions
Why does the PBX send the number before I finish dialing?
Some phones and PBXs send the number as soon as it matches a short dialing rule. If the rule accepts, say, eight digits, a nine-digit mobile number is sent incomplete and comes back as a 484. Adjust the phone's dial plan and the PBX's outbound rules to the current formats.
Which Q.850 cause comes with a 484?
Under RFC 3398, Q.850 cause 28 (Invalid number format, address incomplete) is converted into 484, and a 484 is translated back as cause 28 when the call crosses into the phone network. So in an interconnection log, the same problem can appear as a 484 on one side and cause 28 on the other.