Warning 15003
WARNING - 15003
Call Progress: Warning Response to Callback URL
Got an HTTP warning in response to the callback URL.
Possible Causes
- Your application returned a 4xx or 5xx HTTP response to Twilio.
Possible Solutions
Ensure your application responds to callbacks with:
- 200 OK
- Content-Type: text/xml
- Valid TwiML
Or respond with 204 No Content and an empty response body.