Telnyx SIP integration

Integrate your Telnyx SIP trunk with Vapi to enable your AI voice assistants to handle calls efficiently. This guide walks you through the complete setup process for both inbound and outbound calls.

Retrieve your Vapi private key

Get your private key

Log in to your Vapi account
Navigate to Organization Settings
In the API Keys section, copy your Private Key

Configure Telnyx for inbound calls

Create a SIP trunk

Go to Voice / SIP Trunking / Create
Select FQDN
Click “Add FQDN”
Select A record type
Set FQDN to: sip.vapi.ai
Port should be 5060 by default

Configure inbound settings

Navigate to the Inbound tab of your SIP trunk
Configure settings as shown:

Assign phone number

Go to the Numbers tab
Assign your acquired phone number to the SIP trunk

Configure SIP invite

Go to Numbers, edit the number you’ll be using
Navigate to Voice settings
Scroll down to find “Translated Number”
Set this value to match your Vapi SIP URI

You can get your Vapi SIP URI when you create a new SIP number through the Phone Numbers tab in the Vapi dashboard. The URI will look like:

sip:<your-unique-id>@sip.vapi.ai

This setting modifies the SIP Invite so invites are correctly routed to your Vapi SIP URI.

Configure Telnyx for outbound calls

Set up outbound authentication

Go to Voice / SIP Trunking / Authentication and routing
Scroll down to “Outbound calls authentication”
Create a new credential for Vapi to use

Create outbound voice profile

Go to Voice / Outbound Voice Profiles
Create a new profile
Name it appropriately
Configure desired destinations
Leave default configuration settings
Assign your SIP trunk
Complete setup Alternatively, go to your SIP trunk / Outbound tab and select your newly created outbound voice profile.

Configure outbound settings

Choose the country you’ll be making most calls to We recommend creating a separate SIP Trunk for each country you aim to be making most calls to.

Add your Telnyx SIP credentials to Vapi

Use the Vapi API to create a SIP trunk credential:

$ curl -X POST https://api.vapi.ai/credential \
>   -H "Content-Type: application/json" \
>   -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY" \
>   -d '{
>     "provider": "byo-sip-trunk",
>     "name": "Telnyx Trunk",
>     "gateways": [
>       {
>         "ip": "sip.telnyx.com"
>       }
>     ],
>     "outboundAuthenticationPlan": {
>       "authUsername": "YOUR_SIP_USERNAME",
>       "authPassword": "YOUR_SIP_PASSWORD",
>       "sipRegisterPlan": {
>             "realm": "sip.telnyx.com"
>         }
>     }
>   }'

Replace YOUR_VAPI_PRIVATE_KEY, YOUR_SIP_USERNAME, and YOUR_SIP_PASSWORD with your actual credentials. If successful, the response will include an id for the created credential, which you’ll use in the next step.

Add your phone number to Vapi

Associate your phone number with the SIP trunk in Vapi:

$ curl -X POST https://api.vapi.ai/phone-number \
>   -H "Content-Type: application/json" \
>   -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY" \
>   -d '{
>     "provider": "byo-phone-number",
>     "name": "Telnyx SIP Number",
>     "number": "YOUR_PHONE_NUMBER",
>     "numberE164CheckEnabled": false,
>     "credentialId": "YOUR_CREDENTIAL_ID"
>   }'

Replace YOUR_VAPI_PRIVATE_KEY, YOUR_PHONE_NUMBER, and YOUR_CREDENTIAL_ID with your actual details.

Assign your voice assistant to handle calls

In your Vapi dashboard, go to the Build section and select Phone Numbers
Click on your Telnyx Number
In the Inbound Settings section, assign your voice assistant to handle incoming calls
In the Outbound Form section, assign your voice assistant to handle outgoing calls

Make outbound calls

To initiate outbound calls through your Telnyx SIP trunk:

$ curl --location 'https://api.vapi.ai/call/phone' \
>   --header 'Authorization: Bearer YOUR_VAPI_PRIVATE_KEY' \
>   --header 'Content-Type: application/json' \
>   --data '{
>     "assistantId": "YOUR_ASSISTANT_ID",
>     "customer": {
>       "number": "CUSTOMER_PHONE_NUMBER",
>       "numberE164CheckEnabled": false
>     },
>     "phoneNumberId": "YOUR_PHONE_ID"
>   }'

Replace all placeholder values with your actual information.

By following these steps, your Telnyx SIP trunk will be fully integrated with Vapi, allowing your AI voice assistants to manage calls effectively.