Vapi is the Voice AI platform for developers.

Vapi AI

1.    SIP Credentials
Head to your Vapi dashboard → Voice API → Endpoints, click on your SIP trunk, and make sure the authUsername and authPassword match exactly what your SIP provider gave you.

    2.    Whitelisted IPs
In that same section, make sure all of your SIP provider’s IP addresses are added. If they’re not whitelisted, Vapi will block the call.

    3.    SIP URI Format
Make sure your provider is sending calls to the correct format:
sip:<yourNumber>@sip.vapi.ai
—or—
sip:<yourNumber>@<credential_id>.sip.vapi.ai (if you’re using credentials)