Hello VAPI.AI Support Team, I need your assistance with setting up a SIP connection to your platform. My provider DTMS has already configured everything on their side and activated the routing. The SIP trunk has been set up to the following address: sip.vapi.ai However, when attempting to connect, DTMS receive a message indicating that authentication is required. Using static IP addresses from your docs fails also. DTMS is unable to perform authentication, as they only handle trunk configuration. They informed me that there might be an additional setting required on your end, or that a specific customer name (or identifier) needs to be defined in the DNS so that the connection is accepted. The affected phone number is +49 800 5099641. Everything on my side appears to be configured correctly. Could you please check why the connection is currently being rejected, or advise how authentication should be handled in this case? Once the connection is successfully established, we plan to activate our account and provide payment information (credit card), as we intend to use your AI assistant for our business. Thank you very much for your help and support.

To resolve the authentication issue, you need to create a SIP trunk credential in Vapi for your DTMS connection. Use the following API call (replace placeholders with your actual details):

bash
curl -X POST "https://api.vapi.ai/credential" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_VAPI_API_KEY" \
  -d '{
    "provider": "byo-sip-trunk",
    "name": "DTMS Trunk",
    "gateways": [{ "ip": "sip.vapi.ai", "inboundEnabled": false }],
    "outboundLeadingPlusEnabled": true
  }'

After creating the credential, associate your phone number with it in Vapi. This should resolve the authentication error—see the [SIP trunk setup guide](https://docs.vapi.ai/advanced/sip/sip-trunk) for details. Source: - [SIP Trunking How to integrate your SIP provider with Vapi](https://docs.vapi.ai/advanced/sip/sip-trunk)

DTMS doesnt accept auth based connections. Just ip based.

@fabianbitter_15952 I remember seeing somewhere to just set empy/dummy authentication values and test it. Im not sure about that but maybe worth a try

DTMS is not able to enter any auth data. So is there any solution out there? Maybe buying a custom dedicated ip? Is it possible with your service?

Send a DM to @kylevapi with your org id and I will get it for you. Alternatively, if you use the /credential endpoint to create an entry for your BYO SIP trunk, it will return the credentialId in the response