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

# Connect Telnyx via SIP Trunking

> Integrate your Telnyx numbers with UponAI using elastic SIP trunking.

<Steps>
  <Step title="Create Elastic SIP Trunking in Telnyx">
    In your Telnyx Mission Control Portal, create a new SIP trunk, select **FQDN** as the type, and give it a name.

    **Add FQDN:**

    * Add `sip.retellai.com` as the FQDN
    * Select **SRV** as the DNS record type

    **Setup Outbound Authentication:**

    * Select **Credentials** as the authentication method
    * Add a username and password — you'll need these when importing the number to UponAI

    <Note>
      Telnyx requires the header `X-Telnyx-Username: <username>` in outbound calls when using credential authentication. You can add custom SIP headers on the Make Outbound Calls page.
    </Note>

    **Setup Inbound Settings:**

    * Number format: `+E.164`
    * Codecs: `G722`, `G711U`, `G711A`
    * Transport: **TCP** (recommended over UDP for reliability)
    * Select your SIP region

    **Setup Outbound Settings:**

    * Create a new outbound voice profile
    * Select it in the outbound setting
  </Step>

  <Step title="Move numbers to your SIP trunk">
    Purchase new numbers or move existing Telnyx numbers to the elastic SIP trunk you just created.
  </Step>

  <Step title="Import numbers to UponAI">
    In the UponAI dashboard, import the number by supplying:

    * **Termination SIP URI** — Telnyx's FQDN based on your SIP region (e.g. `sip.telnyx.com`)
    * Username, password, and any additional SIP headers from your outbound authentication setup

    You can also import numbers programmatically via the Import Number API.

    Once imported, the number behaves like a UponAI-purchased number — visible in your dashboard, usable for inbound and outbound calls. Delete it from the dashboard or via the Delete Number API when no longer needed.
  </Step>
</Steps>