---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/15003#article
headline: "15003: Call Progress: Warning Response to Callback URL"
url: https://www.twilio.com/docs/api/errors/15003
inLanguage: en
dateModified: 2026-03-11T18:38:39.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 15003: Call Progress: Warning Response to Callback URL

Log Type: APPLICATION

Log 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.