Hi, i have one BYO trunk defined for inbound calls. Working fine combined with phone number and assistant. When I add 1 new phone number using the same assistant and BYO inbound trunk the call isn't setup up. In my SBC logs I see an '503 Service Unavailable - Multiple accounts are attempting to default route this carrier'. Even when a link this new phonenumber to another assistantm the same result. Any ideas how to fix this?

Hi martyvandeveerdonk, I see that you're looking for information related to setting up outbound calling with a BYO SIP trunk. Here are some steps to guide you: 1. **Configure Your SIP Provider**: Ensure you have configured your SIP trunk through your provider (like Plivo). You'll need to create an outbound trunk and enter specified IP addresses in the access control list. 2. **Get Your Plivo Termination SIP Domain**: When you set up your trunk, note your termination SIP domain as you'll need it for your Vapi configuration. 3. **Set Up Vapi**: - Log into your Vapi dashboard and get your API key. - Run a POST request to create a credential for your SIP trunk using the termination SIP domain:

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

4. **Associate Phone Number**: - Purchase a number through your SIP provider and associate it with the trunk:

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

You can find more detailed steps and example code in our [Plivo SIP Integration](https://docs.vapi.ai/advanced/sip/plivo) documentation. Make sure to replace placeholders with actual values specific to your setup. Feel free to proceed with these steps and let us know if you encounter any issues.