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SIP response code 408

  • Article
  • Applies to:
    Microsoft Teams

This article provides troubleshooting information for various combinations of the SIP 408 error and Microsoft response codes.

1106 408 An acknowledgement was not received for the call acceptance in the allotted time

  • Microsoft response code: 1106
  • SIP response code: 408
  • Suggested actions:
    • This error indicates that the callee answered the call, but the Session Border Controller (SBC) didn't acknowledge the SIP 200 OK (answer message) from Microsoft. Work with your SBC vendor to verify that the SIP stack and the underlying TCP/TLS connections are correctly established with Microsoft connection points.

500001 408 Gateway (SBC) failover timer expired

  • Microsoft response code: 500001

  • SIP response code: 408

  • Suggested actions:

    • Investigate why the SBC didn't send a response to the invitation within the configured time-out value, as defined by FailoverTimeSeconds. The default value is 10 seconds.

    This error usually occurs in regions that have long PSTN setup times. Consider changing the failover timer to 20 seconds in these regions or on all Direct Routing trunks.

560408 408 SBC indicated that the user did not respond (request timeout)

  • Microsoft response code: 560408
  • SIP response code: 408
  • Suggested actions:
    • Review the tenant's call records that include CallEndSubReason = 560408. Look for trends in the called numbers, or a distribution of the failures by destination country/region. Patterns can be identified that would suggest a problem that affects a downstream component.

0 408 Establishment timeout

  • Microsoft response code: 0
  • SIP response code: 408
  • Suggested actions:
    • This code indicates a client error. Check the network connection between the client and the Teams service.