> ## Documentation Index
> Fetch the complete documentation index at: https://docs.custral.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshooting

> Fixes for texts that won't deliver, opt-outs, inbound routing, and number issues.

## Overview

Two-way SMS runs on Twilio numbers connected as Channels. In the US, most **delivery** problems trace back to A2P registration; **inbound** problems trace back to number connection and routing. Start with the table, and see [A2P registration](/comms/sms/a2p-registration) for registration-specific fixes.

## Common issues

| Symptom                                       | Likely cause                                                                 | What to check                                                                                                                                         |
| --------------------------------------------- | ---------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- |
| Outbound texts **never arrive** (US)          | Workspace isn't A2P-registered, or the campaign isn't active                 | **Settings → Phone & SMS → Compliance**, is the Campaign **active**? See [A2P registration](/comms/sms/a2p-registration).                             |
| "This recipient has **opted out**"            | The contact replied STOP                                                     | They must reply **START** to opt back in. Opt-outs can't be overridden.                                                                               |
| Can't send from a number, or it isn't offered | The number isn't SMS-capable, or isn't connected as an SMS Channel           | Use an SMS-capable number connected as a Channel of type `sms`.                                                                                       |
| Send **fails with a Twilio error code**       | Invalid number format, opt-out, or a carrier block                           | The failure and code are recorded on the Conversation timeline; permanent blocks auto-add the number to [Suppressions](/comms/suppressions/overview). |
| **Inbound** texts don't appear                | The number isn't connected as a Channel                                      | Confirm the destination number is a connected SMS Channel.                                                                                            |
| Inbound goes to the **wrong person**          | Routing rules                                                                | Rules evaluate top-down, first match wins. Check the channel's [routing rules](/comms/sms/receiving) and its default assignment.                      |
| **MMS** image doesn't show                    | MMS is US/CA only and media is best-effort                                   | Confirm the number supports MMS.                                                                                                                      |
| Hitting a **rate / throughput cap**           | Twilio per-segment and per-day limits (lower on a Sole Proprietor A2P brand) | Space out sends; a Standard brand has higher throughput.                                                                                              |
| Reply doesn't appear **live**                 | Socket / room hiccup                                                         | Reload the conversation. The message is still recorded.                                                                                               |

<Note>
  When reporting an issue, include the **request id** shown in the error toast. It links the in-app error to the server
  logs.
</Note>

## Related

* [A2P registration](/comms/sms/a2p-registration) · [Sending SMS](/comms/sms/sending) · [Receiving SMS](/comms/sms/receiving) · [Deliverability](/comms/deliverability/overview)


## Related topics

- [Troubleshooting](/comms/deliverability/troubleshooting.md)