The error you're seeing is because Vapi numbers have a daily limit of 10 outbound calls. To resolve this issue, you'll need to import your own Twilio number which allows unlimited outbound calls.
Here's how to do it:
1. Purchase a number through Twilio
2. Navigate to the "Phone Numbers" section in Vapi dashboard
3. Click the "Import" button
4. Enter your phone number and Twilio credentials (Account SID & Auth Token)
According to [Vapi documentation](
https://docs.vapi.ai/quickstart/phone/inbound), this will bypass the daily call limit restriction.
Source:
- [Vapi documentation](
https://docs.vapi.ai/quickstart/phone/inbound)