---
page_type: error
code: 13807
message: "13807: Client Notification URL Error Response"
level: ERROR
product: Programmable Voice
---

## Description

The Client Notification URL returned an error.

### Possible Causes

- Your URL is returning 5xx error due to an internal server issue
- Your URL is returning a 400, 401, or 403 due to a server misconfiguration or authentication/authorization issue
- Your URL returned a 404 due to a misconfiguration of your `clientNotificationUrl` in your TwiML or API request
- Your URL returned a 404 because your application could not find a binding for the user receiving the call

### Possible Solutions

- Resolve your server errors
- Reconfigure your `clientNotificationUrl` to the correct URL
- Remove the user who has no binding from your call routing
- Return a 200 OK
- Verify you are using [Client Call Notification Webhook](/docs/voice/sdks/call-notification-webhook) correctly