No missed call notifications on busy

Frequent Contributor

Hello all,


since a while I experience a changed behaviour when receiving calls in case I'm busy on another call/meeting. The option "Busy on busy is available when in a call" in Teams Calling Policies is set to "Enabled" and assigned to the users.




Teams Direct Routing is configured with an Audiocodes Mediant VE 7.20A.258.661. Everything works as expected except missed call notifications on busy.


Past (probably a few weeks ago)

  • In the past I was on a call, busy, and another person was calling.
  • The other person is receiving a busy tone and
  • the call gets rejected, as should.
  • I then got a missed call notification in my missed calls.


  • I'm on a call, busy, and another person is calling
  • The other person is receiving a busy tone and
  • the call gets rejected, as should.
  • I DO NOT get a missed call notification in my missed calls (issue)


  • The SBC logs are fine showing SIP 486 Busy.
  • I could not recognize a change here.
  • Microsoft Phone System to SBC:
    • SIP 486 
    • REASON: Q.850;cause=34;text="...;User is busy and currently active on another call."
  • SBC to Provider:
    • SIP 486
    • Manipulated SIP Header Reason Cause Code from 34 to 17;
      34 is sent bei MS Phone System to the SBC is wrong, IMO)
    • Reason: Q.850 ;cause=17 ;text="...;User is busy and currently active on another call."


I deleted the Teams client cache on Windows but this did not make a difference.

I can reproduce the issue everytime. I can reproduce it in other Teams Direct Routing deployments as well.


So, did this behaviour change? Is it a Teams (client) bug? Is anyone else experiencing this changed behaviour?


I wrote a blog about an issue last year where the behaviour for missed notifications on the Teams Clients was different. Call loops after enabling busy on busy for Microsoft Teams Calling with Audiocodes Mediant – Erik's ...


The documentation does not state anything regarding missed call notifications in case of a call is rejected due to busy on busy is enabled as far as I could see. Set up policies - Microsoft Teams | Microsoft Docs


Best Regards


7 Replies
Hi Erik,

the same on my side and I´m just working with MS Support on that case.

I´m not sure, but I think there is a new BoB option called "unanswered" and in Client config is (i would say) also a new option "do nothing". Maybe that´s the starting point with this issue.

BR, Matthias

Hi @GerkensM,


Thank you!

I 'd guess that something was changed due to new / changed busy options. True, as you said, since a while you can not only just enable/disable busy on busy, you can also select "unanswered" which uses the user's unanswered setting.


Best Regards,


Yep. Obviously a bug. Premier Support is clueless and has ceased communications. Let's hope that it will be resolved in the next weeks…

strange, my Signin GerkensM doesn´t work.

here is the answer from MS support
I've just received an update that a bug has been identified recently regarding the issue (yesterday) by our highest level of Engineering.

The ETA for a resolution currently is - the end of Next Week.
best response confirmed by Erik365Online (Frequent Contributor)
Support confirmed this bug:
"BUG - Bug 2523318: CC: Fix missing CallLogs and MissedCalls for Target in Busy on Busy - Boards"
Thank you for sharing the information regarding the bug. Good to hear that's worked on it.
I'll provide this information to my "assigned" Microsoft Support Engineers.
The fix reached our tenant today. yeah