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Microsoft and SIP response codes

When you troubleshoot Direct Routing issues, the specific cause of a call failure can be identified through a combination of the following response codes:

  • SIP response code (CallEndReason): A three-digit response code that shows the request status. This code is received from the Session Border Controller (SBC) or Direct Routing SIP interface. It explains what occurred. For example, the SBC didn't reply in a timely manner. The SIP response codes are defined in RFC 3261.
  • Microsoft response code (CallEndSubReason): A response code that's assigned by Microsoft. This code is usually six digits long, but it might be reported as 0 digits or more than six digits, depending on the problem. It explains why the problem occurred. For example, the certificate on the SBC expired.

These response codes are reported in the Microsoft Teams admin center and the Power BI Quality of Experience Report (QER) for PSTN.

Direct Routing error codes

A key factor in troubleshooting Direct Routing issues is determining whether the final response code is generated by Microsoft or by the SBC. An easy way to determine this is to look at the Microsoft response code.

  • If the Microsoft response code starts with 560, it indicates that the final SIP response code is generated by the SBC. For example, if the Microsoft response code is 560403, it means that the final response code is generated by the SBC, and the last three digits indicate SIP response code 403. In this case, start troubleshooting by using the SBC logs. Also, see the additional information in the following content. We recommend that you seek assistance from your SBC vendor.
  • For all other Microsoft response codes that do not start with 560, the final SIP response code is generated by a Microsoft service.

For more information about the most common errors and suggested actions to further troubleshoot and mitigate the issue, select a SIP response code from the following list: