> For a complete page index, fetch https://docs.synthflow.ai/llms.txt. For full documentation content, fetch https://docs.synthflow.ai/llms-full.txt.

# Twilio

> Connect your Twilio account to Synthflow for voice and SMS capabilities across agents and messaging channels.

![Twilio integration card in the Synthflow dashboard, showing a 'How it works' summary, Docs and Website links, and an Install App button](https://files.buildwithfern.com/synthflow.docs.buildwithfern.com/0b3925587cf0c96182a06ddf7d0eded38c7f083010e60d1775683b5e248169fd/docs/assets/screenshots/twilio_1.png)

Bring your own Twilio account so your Synthflow agents can place and receive calls, send SMS, and run on existing telephony infrastructure. Numbers stay in Twilio while routing, recording, and [call transfers](/call-transfers) run through Synthflow.

<Warning>
  If your Twilio account is already trunked into other systems, create a Twilio subaccount for the number you connect to Synthflow so the integrations don't interfere with each other.
</Warning>

## Connect your Twilio account

In the Synthflow dashboard, open **Integrations > Twilio** and paste your Twilio **Account SID** and **Auth Token**. If you can't find them, see Twilio's [guide to locating your Account SID and Auth Token](https://help.twilio.com/articles/14726256820123-What-is-a-Twilio-Account-SID-and-where-can-I-find-it-). For enterprise SIP trunking setups, see [SIP integration with Twilio](/sip-with-twilio).

## Install from the Twilio Marketplace

If you manage Twilio first, install Synthflow from the [Synthflow AI listing in the Twilio Marketplace](https://console.twilio.com/us1/develop/add-ons/catalog/XB2cc83ef68b5e11a55c06cc358a50c0f7) to layer voice AI agents on top of your existing Programmable Voice, Flex, or WhatsApp setup without changing your telephony stack.

![Synthflow AI listing in the Twilio Marketplace, with product tags for WhatsApp, Programmable Voice, and Flex, plus an Install button](https://files.buildwithfern.com/synthflow.docs.buildwithfern.com/82f2435f2a36d11fbd6e1e39284152ab6105bcc898fef138953dd62653de54cb/docs/assets/screenshots/twilio_synthflow_app.png)

## Regional API routing \[#regional-api-routing]

Twilio operates regional infrastructure (`US1`, `IE1` for Ireland, and others). Not every Twilio product runs in every region: requests for products that don't support `IE1` automatically fall back to `US1`. This only matters when you bring your own Twilio integration into an [EU workspace](/customer-region) and want to keep voice traffic on European infrastructure.

The table below shows where each Twilio request that Synthflow makes is processed when an EU workspace is connected to your own Twilio account. Sourced from Twilio's [Regional product availability](https://www.twilio.com/docs/global-infrastructure/regional-product-and-feature-availability) docs.

| Synthflow feature                                                                  | Twilio product                    | Region   |
| ---------------------------------------------------------------------------------- | --------------------------------- | -------- |
| Inbound and outbound calls                                                         | Programmable Voice                | EU (IE1) |
| Call recording                                                                     | Programmable Voice Recording API  | EU (IE1) |
| [SIP transfers](/call-transfers#sip-transfers) and SIP trunking                    | Elastic SIP Trunking              | EU (IE1) |
| Phone number lookup                                                                | Lookup v2                         | EU (IE1) |
| [Send SMS](/how-to-create-a-send-sms-action) and [in-call SMS](/in-call-messaging) | Programmable Messaging            | US (US1) |
| [WhatsApp messaging](/whatsapp-business-calling)                                   | Programmable Messaging (WhatsApp) | US (US1) |
| [Phone number purchase](/buy-a-phone-number)                                       | PhoneNumbers API                  | US (US1) |

### Find your IE1 token

To route the EU-eligible operations above through Twilio's Ireland region, the credentials you connect must be issued in `IE1`. Twilio resources (API keys, TwiML applications, call logs) are isolated per region, so an `IE1` API key can only manage `IE1` resources.

To find or create an Ireland-region credential:

1. In the Twilio Console, open the **Account** menu in the upper right and select **API keys & tokens** under **Keys & Credentials**.
2. In the **Region** dropdown at the top right of the page, switch to **Ireland (IE1)**.
3. Copy the IE1 **Auth Token**, or click **Create API key** (Standard or Main) to issue a new IE1 key.
4. Paste those credentials into Synthflow's **Integrations > Twilio** under the **regional token field**.

![Walkthrough of locating the Ireland-region Account SID and Auth Token inside the Twilio Console](https://files.buildwithfern.com/synthflow.docs.buildwithfern.com/76bed70469c78f4af88f2987f0746f71ba373951030a28f06def6ba5d90462c0/docs/assets/screenshots/twilio_regional_token_compressed.gif)

For full details, see Twilio's [Manage Regional API Credentials](https://www.twilio.com/docs/global-infrastructure/manage-regional-api-credentials) and [Using the Twilio REST API in a non-US Region](https://www.twilio.com/docs/global-infrastructure/using-the-twilio-rest-api-in-a-non-us-region) guides.

## Compliance \[#compliance]

Twilio enforces regulatory and messaging requirements that affect any Synthflow deployment running on your own Twilio account:

* **Voice calls** must follow Twilio's [regulatory guidelines](https://www.twilio.com/en-us/guidelines/regulatory) for each country you operate in. Create a regulatory bundle in the Twilio console and submit it for review with up-to-date documentation.
* **SMS** must follow Twilio's [A2P 10DLC regulations](https://www.twilio.com/docs/messaging/compliance/a2p-10dlc). Register your brand and campaign use case with The Campaign Registry; the resulting trust score determines your message throughput and protects messages from carrier filtering.

When a Synthflow call or message fails unexpectedly, compliance is the first thing to check:

* **A2P SMS errors** lead to messages being filtered or blocked. Confirm your messaging service matches the registered campaign.
* **Regulatory errors** lead to call completion failures. Confirm country-specific documentation is on file in your Twilio console.

## External Twilio resources

Reference docs for the Twilio products and policies mentioned on this page:

* [Account SID and Auth Token](https://help.twilio.com/articles/14726256820123-What-is-a-Twilio-Account-SID-and-where-can-I-find-it-): find your credentials in the Twilio console.
* [Regional product availability](https://www.twilio.com/docs/global-infrastructure/regional-product-and-feature-availability): which Twilio products run in which region.
* [Manage Regional API Credentials](https://www.twilio.com/docs/global-infrastructure/manage-regional-api-credentials): create and manage region-specific Auth Tokens and API keys.
* [Using the Twilio REST API in a non-US Region](https://www.twilio.com/docs/global-infrastructure/using-the-twilio-rest-api-in-a-non-us-region): target the Ireland (`IE1`) region with regional credentials.
* [Regulatory guidelines](https://www.twilio.com/en-us/guidelines/regulatory): country-by-country requirements for placing calls.
* [A2P 10DLC](https://www.twilio.com/docs/messaging/compliance/a2p-10dlc): register your brand and campaign for SMS deliverability in the US.
* [Geo-permissions](https://www.twilio.com/docs/verify/preventing-toll-fraud/verify-geo-permissions): enable calling for specific destination countries.
* [Synthflow AI listing in the Twilio Marketplace](https://console.twilio.com/us1/develop/add-ons/catalog/XB2cc83ef68b5e11a55c06cc358a50c0f7): install Synthflow from inside the Twilio Console.

## FAQ

<AccordionGroup>
  <Accordion title="How do I import phone numbers and other data?">
    You can import phone numbers from Twilio. Other phone providers are available on Enterprise plans only; contact sales to discuss access.
  </Accordion>

  <Accordion title="How do I add Twilio to my subaccounts?">
    Twilio subaccounts let you delegate a phone number to a separate set of credentials. Each subaccount has its own Account SID and Auth Token that only grant access to the numbers delegated to it.
  </Accordion>

  <Accordion title="Why is Twilio not allowing me to call customers located in certain countries?">
    Enable the relevant settings in [Twilio's geo-permissions guide](https://www.twilio.com/docs/verify/preventing-toll-fraud/verify-geo-permissions).
  </Accordion>
</AccordionGroup>