By Alpit Patel and the aibrevo team · October 22, 2026 · 6 min read
What Do GoHighLevel Error Codes 31005, 31603 and 12300 Mean?
Quick answer
All three are Twilio error codes, and none is in HighLevel's own phone error dictionary. 31005 is a dropped call connection, 31603 is a declined call or an inactive Twilio account, and 12300 is a webhook returning a bad Content-Type. This page gives each code's cause and the check to run first.
Key takeaways
- Error 31005 is Twilio's Connection error: the WebSocket to Twilio's signaling servers closed unexpectedly during a call. Twilio names DNS failures, a bad region value, firewalls and a client going offline as causes.
- Error 31603 is Twilio's Decline. Either the person called rejected the call (SIP 603), or Twilio received SIP traffic for an account that is not active, for example one suspended over an unpaid balance.
- Error 12300 is Invalid Content-Type: a webhook, action URL or Play verb pointed at a resource that is not XML or audio, or a server that sent no Content-Type header.
- HighLevel's LC Phone error dictionary (modified Sep 8, 2026) lists 22 codes, all in the 21xxx and 30xxx ranges. It does not list 31005, 31603 or 12300 (checked Oct 22, 2026).
- Twilio's definitions are the best public reading, but HighLevel does not publish how it surfaces these three, so test before assuming the Twilio cause applies.
Error codes 31005, 31603 and 12300 are Twilio error codes, and none of them is in HighLevel’s own phone error dictionary. In Twilio’s reference, 31005 is a dropped call connection, 31603 is a declined call (or an inactive Twilio account), and 12300 is a webhook that returned the wrong Content-Type. That is what the codes mean in Twilio. Whether your GoHighLevel screen shows the Twilio cause or something wrapped around it is something HighLevel does not document.
Checked Oct 22, 2026 against three Twilio error pages and HighLevel’s LC Phone error code and warning dictionary (modified Sep 8, 2026). We did not reproduce these errors in a live account, so the fix order below is from the documents.
Why are these codes not in HighLevel’s error list?
HighLevel’s dictionary covers 22 codes: 21211, 21408, 21614, 21635, 21661, 21610, 21612, 21606 and the 30xxx group (30002 to 30008, 30011, 30023, 30032 to 30035, 30037). That is mostly the text-message side, which is why guides like our SMS error code guide can map failures to fixes. Nothing in it starts with 31 or 12.
The 21xxx and 30xxx families are Twilio-style numbers too, and HighLevel’s own help pages say Twilio remains supported alongside LC Phone, as covered in using your own Twilio account with GoHighLevel. So Twilio’s public reference is the sensible place to look up a code HighLevel leaves out. Treat it as a definition of the code, and a lead on the cause, not proof of it.
| Code | Twilio’s title | Applies to | Seen in HighLevel’s dictionary |
|---|---|---|---|
| 31005 | Connection error | Voice calls over a WebSocket connection | No |
| 31603 | Decline | Calls and SIP termination | No |
| 12300 | Invalid Content-Type | Webhooks, action URLs, Play | No |
Source: Twilio error reference pages for each code and HighLevel’s LC Phone error dictionary, checked Oct 22, 2026.
What does error 31005 mean, and what do I check first?
Twilio’s definition: “The WebSocket connection to the Twilio signaling servers closed unexpectedly during the call.” It is the connection, not the person on the other end. Twilio lists these causes:
- DNS or hostname resolution failing for the signaling endpoint.
- An invalid
regionvalue set during device setup. - Network conditions such as a restrictive firewall, the client going offline, or an unreachable Edge.
Twilio’s fixes are to confirm the signaling hostname resolves, to check any region value, to allow outbound TCP port 443 to the Twilio Voice signaling gateways through the firewall, and to let the SDK reconnect after a network change (it can wait up to 30 seconds if maxCallSignalingTimeoutMs is set).
For a GoHighLevel user the first two are developer settings you do not control. The third is yours. If the error appears when calling from a browser or phone app, try a second network such as a phone hotspot, close VPNs, and ask the office IT person whether outbound port 443 is filtered. If it works on the hotspot and fails on the office network, the firewall is the answer. That route is our inference from Twilio’s text, since HighLevel does not describe how its calling client connects.
What does error 31603 mean, and is the number or the account at fault?
Twilio defines it as the called person declining: a SIP 603 Decline. Two causes are listed:
- The called party rejected the call. Nothing is broken. A person hit decline, or a phone or carrier service rejected it.
- SIP termination traffic for an inactive account. Twilio says this can happen when the account was closed or suspended for an unpaid balance or a policy violation, and that the response carries an
X-Twilio-Errorheader with code 10001.
So test before you worry. Call two or three different numbers. If most connect and one fails, that number declined. If every outbound call fails and you run your own Twilio account, sign in to Twilio and confirm the account is active and funded. If you use LC Phone, the account side belongs to HighLevel, so check your wallet balance and open a support ticket with the call log entry. Our page on wallet auto-recharge and billing explains how the balance works. HighLevel’s pages we read do not say that an empty wallet produces 31603, so treat that as a check, not a diagnosis.
If calls reach people but they see “Spam Likely” and decline, that is a reputation problem, covered in why GoHighLevel calls show as spam likely.
What does error 12300 mean?
Twilio’s wording: it “can’t process the Content-Type of the URL you provided.” Every request needs a Content-Type header, and requests without one show up in Twilio’s Debugger as 502 Bad Gateway errors. The cause is a phone number, outgoing call request or action attribute pointing at a resource that is not XML or audio, or a Play verb trying to play something that is not audio, such as XML or text.
You will mostly meet it if you connect your own Twilio account and route calls through a custom webhook or a Twilio Function. Fix it on the server that answers: send a Content-Type header, make sure its value is the one Twilio expects (XML for call instructions, an audio type for Play), and confirm the URL in the error points at the right resource. If you only use LC Phone with the built-in workflow actions, you have no URL of your own to correct, and the code points to something HighLevel should look at.
How do I know which layer an error came from?
Match the symptom to the layer as well as the number.
| Symptom | Likely layer | First check |
|---|---|---|
| Call drops mid-ring on one network only | Your network | Hotspot test, firewall port 443 |
| Calls to one person always fail, others connect | The called party | Different number, ask them |
| Every outbound call fails at once | Account | Twilio or wallet balance, support ticket |
| Error appears after you add a webhook URL | Your server | Content-Type header on the response |
| Texts fail with 30007, 30034, 21610 | Messaging | SMS error code guide |
Source: our symptom mapping from Twilio’s cause lists, checked Oct 22, 2026. It is a reading aid, not a HighLevel statement.
When to get help
Get help when calls fail for a clinic or sales team during business hours, when your own Twilio account is wired to HighLevel through custom webhooks, or when you cannot tell whether the fault sits with Twilio, HighLevel or your network. A specialist can read the call logs, check the phone setup and webhook responses, and write the exact ticket HighLevel needs. Send a message or book a short call, and see the GoHighLevel service page for the work aibrevo does.
Sources
All checked Oct 22, 2026.
- Twilio, Error 31005: Connection error: definition, causes, fixes.
- Twilio, Error 31603: Decline: definition, SIP termination case, X-Twilio-Error header.
- Twilio, Error 12300: Invalid Content-Type: definition, causes, fixes.
- HighLevel Support Portal, LC Phone System: error code and warning dictionary (modified Sep 8, 2026): the 22 listed codes.