How do I resolve the delivery failure error code 4452?

If your outbound messages are failing with an error code 4452, it means the Application ID in your POST request to our /messages endpoint is incorrect. The Application ID is required for your POST request when using our messaging API. 

To resolve this issue, please complete the following steps to verify the messaging Application ID your number is assigned to:

1. Log into the Bandwidth Dashboard.
2. In the Search Telephone Numbers section, enter the phone number and click Search.

3. In the Search Results section, click the phone number link. This will take you to the Phone Number Details page.

4. Click the link next to Location.

5. Select the Messaging tab and scroll down to the Applications field to find the name of the messaging application.

6. In the top navigation bar, select Applications.
7. Select the application from the list on the left.
8. The correct Application ID is displayed in the Application ID field. Please use it to update your JSON payload and retry your message.