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

# Telnyx

> Connect Telnyx to Synthflow via SIP trunking so Telnyx numbers and routing can work with your AI agents.

A Telnyx SIP trunk connects your Telnyx numbers to Synthflow, so agents place and receive calls on them. You create the trunk in Telnyx, then import each number into Synthflow.

## Telnyx SIP trunk

* **1. Trunk.** Create the SIP trunk, select **FQDN** as the type, and give it a name.
  * ![](https://files.readme.io/f7a3ff684461182ef964424921331785d88abd4a8332b5e4341d3c0edddfb343-image.png)

* **2. Synthflow FQDN.** Add the FQDN of Synthflow's SIP server:
  * Select `A` as the DNS record type.

  * Enter `sip.synthflow.ai` in the **FQDN** field. For US or EU workspaces, use your region's [SIP address](/connect-over-sip#sip-addresses) instead.

  * Enter `32681` in the **Port** field.

  * ![](https://files.readme.io/d63f112b57b704703b76ec7ea28cda168f0e38ee4ef44b9c161ef4fe3beeb5ae-image.png)

    ![Telnyx Add FQDN modal with the Synthflow SIP server and port 32681](https://storage.googleapis.com/granular-changelog/doc-images/telnyx-add-fqdn-modal.png)

* **3. Outbound authentication.** Select credentials as the authentication method, and add a username and password. You enter the same username and password when you import the number into Synthflow.

  * ![](https://files.readme.io/2234ea6dc96e82a1abcbf855ae6ca139a8b6c0f8d56df8914bfcc3544822ab33-image.png)

* **4. Inbound settings.** Select `+E164` as the number format, and `G711` and `OPUS` as the codecs.

  * ![](https://files.readme.io/f5b83df34992ffd30378dc89eb088b0c0776f07a4e72c3cb83ecce2bfd2d7e57-image.png)

![](https://files.readme.io/15f6d830193ceffdd4bc53e202ad47012aeaeae140fea063adbe98914454e3d9-image.png)

* **5. Outbound settings.** Create an Outbound Voice Profile and select your **SIP region**.

* * ![](https://files.readme.io/6496405e7f740f46d6c0fc06c45f17a8eebc266fc2c130a69b3205fd1e527c9a-image.png)

    ![](https://files.readme.io/5205a046f8f1aa7d04665ce9313cc6b79dbaa940f81c287bbdee5b8ecc1a7e91-image.png)

    ![](https://files.readme.io/77006fa3eb5d7a8775c08a44474ffec7748725da5ec8189228854f5d5f392e5b-image.png)

    Go back to the SIP trunk, open the **Outbound** tab, and select the voice profile you created.

    * ![](https://files.readme.io/ae29d6fe2f32528e3dd547807be23a477ea1af21c79c45b5bfb36394a4867ca9-image.png)

* **6. Numbers.** Buy numbers in Telnyx, or move your existing numbers, and assign them to the trunk.

  * ![](https://files.readme.io/8f8f918625529e4628dee3aed4904d85c04ea66093ee79d1877213c949586367-image.png)

    ![](https://files.readme.io/c06039422560773bd7c320a4333ad0df6dd9056914f2d76ec416bd2a141fc64c-image.png)

## Number import

Import each number into Synthflow as a [custom number](/phone-numbers#adding-custom-numbers), so Synthflow knows how to route its calls.

![](https://files.readme.io/34dffa668dc7381fd822616bcfaccdeaa27ec998c25c6edf224d9c231a32296e-image.png)

* Enter `sip.telnyx.com` as the termination SIP URI.
* Enter the username and password from step 3.

![](https://files.readme.io/b4aba0a64cfc305c0dc056792d8226f939ffeb02f13c57e43db4b160bcb4ff26-image.png)

The imported number places and receives calls like a number bought in Synthflow. To stop using it, delete it from **Phone Numbers**, or with the [Delete a phone number](/api-reference/platform-api/phone-numbers/delete-phone-number) API.

> Route Telnyx numbers to Synthflow agents over a Telnyx SIP trunk.