> ## 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.

# Twilio

> Provision numbers, send SMS, and place voice calls.

## What it does

Twilio powers every SMS and voice channel. Custral provisions or imports Twilio numbers, sends outbound SMS and voice through them, and receives inbound calls and texts on them.

## Connect

<Steps>
  <Step title="Connect a Twilio account">
    **Settings → Channels → Twilio**. Paste your Account SID and Auth Token.
  </Step>

  <Step title="Provision or import a number">
    Use the in-app flow to buy a new number from Twilio's inventory, or import a number you already own.
  </Step>

  <Step title="Pick personal vs shared">
    Personal numbers route to one user; shared numbers route through a channel pool with assignment rules.
  </Step>
</Steps>

## Configure

Per number:

* **Recording on / off** for voice.
* **Routing rules** for inbound.
* **Compliance**: 10DLC registration for US SMS volume.

Per workspace:

* **Channel pools** for outbound dial-from rotation.

## Resources synced

| Resource            | Custral surface                                        |
| ------------------- | ------------------------------------------------------ |
| Phone number        | An SMS or voice channel.                               |
| Inbound SMS         | A message in the conversation.                         |
| Inbound call        | A conversation with recording and transcript.          |
| Outbound SMS / call | A message in the conversation, with a delivery report. |

## Limitations

* MMS (image / video attachment) supported on US/CA numbers only.
* 10DLC registration is required for US SMS at scale; Custral surfaces the registration UI but the application is filed with Twilio directly.
* Conference calling (3+ parties) is on the roadmap.

## Troubleshooting

| Symptom                          | Fix                                                                                         |
| -------------------------------- | ------------------------------------------------------------------------------------------- |
| SMS to a recipient keeps failing | The recipient has opted out. They must text `START` to re-subscribe.                        |
| Call quality degrades            | Confirm the recipient has a stable connection; check your Twilio account's region settings. |
| Inbound number stops ringing     | Re-save the number under **Settings → Channels** to refresh its routing.                    |

## Disconnect

Releasing a number from Custral deletes the Channel but does not auto-release the Twilio number, release it from the Twilio console if you no longer want to be billed for it.

## See also

* [SMS overview](/comms/sms/overview)
* [Voice: Numbers](/comms/voice/numbers)


## Related topics

- [Phone & SMS Numbers](/comms/voice/numbers.md)
- [Receiving SMS](/comms/sms/receiving.md)
- [Sending SMS](/comms/sms/sending.md)
- [SMS](/comms/sms/overview.md)
- [Integrations](/integrations/overview.md)