@mehdi It seems like there might be an issue with the payload you're sending or with the API key. A 400 status code typically indicates a bad request, which means there could be something wrong with the data you're providing to the API. Here are a few things you can check: 1. **API Key**: Ensure that the

VAPI_API_KEY

in your environment variables is correct and has the necessary permissions for making outbound calls. 2. **Payload Validation**: Double-check the payload structure against the VAPI documentation to ensure all required fields are present and correctly formatted. Make sure

to

,

phoneNumberId

, and

assistantData

variables are populated with valid data. 3. **Headers**: Verify that the

Content-Type

header is set to

application/json

and that the

Authorization

header is correctly formatted with the Bearer token. 4. **Endpoint URL**: Confirm that the endpoint URL

https://api.vapi.ai/call

is correct and that the API hasn't changed its base URL or endpoint path. 5. **Error Details**: Look for any additional error information provided in the response body, as it may give more insight into what's going wrong. If you've checked all of these and are still encountering issues, please provide more details or error messages if available, so I can assist you further. If the problem persists, you may need to contact support for more in-depth troubleshooting.