Share via

SIP response code 400

  • Article
  • Applies to:
    Microsoft Teams

This article provides troubleshooting information for the combination of the SIP 400 error and Microsoft response code 540400.

540400 400 Bad Request

  • Microsoft response code: 540400
  • SIP response code: 400
  • Suggested actions:
    • Check the SBC configuration to determine why it sends an invalid or unsupported SIP message format to Microsoft and fix any misconfiguration.