---
page_type: error
code: 15003
message: "15003: Call Progress: Warning Response to Callback URL"
level: WARNING
---

## Description

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.