Teams Only - Skype Interoperability - Unable to communicate bidirectionally Teams only mode to on-prem Skype user homed on Lync Server 2013

Question

Hello, requesting for someone to please help us out:

• We have an on-premise Lync Server 2013 Standard edition environment, with all CSUser objects homed on-premise at the moment
• We have hybrid mode enabled between our on-premise Lync Server 2013 Standard edition environment and our Skype for Business Online tenant
• From https://admin.microsoft.com we show all green check-marks for public DNS SfBO services indicating our public DNS settings are configured properly
• Our on-premise homed CSUser objects within the Teams tenant show an "InterpretedUserType" of "HybridOnPremSfBUserWithTeamsLicense"
• Our on-premise homed CSUser objects within the Teams tenant show "SfBWithTeamsCollab" as the "TeamsUpgradeEffectiveMode" and "TeamsUpgradePolicy" (Coexistence Mode)
• We have successfully migrated approx 25 CSUser objects off of on-premise Lync Server 2013 Standard edition to SfBO, and those test accounts show as an InterpretedUserType of "HybridOnlineTeamsOnlyUser" (fully migrated CSOnlineUser objects now homed in Microsoft Teams)

Based on this article:

https://learn.microsoft.com/en-us/microsoftteams/teams-and-skypeforbusiness-coexistence-and-interoperability

bidirectional communication should work Teams to Skype. Currently in our environment, we can only initiate a chat from the on-premise homed CSUser using Skype, when that person sends a chat to the Teams only mode homed CSOnlineUser object. When that Teams only mode user tries to reply back to the IM, we get an error 404/1033 - (SIP error indicating that the "User cannot be found"). We've troubleshot all network ports, we have internal Lync FE servers with DMZ located Lync Edge servers all ports are open and operational. We have a case open with Microsoft for the last 2 months now and have yet to get any resolution to this issue. Please help with any comments or suggestions you might have.

Answer 1

Thank you for your response JimmyYang-MSFT - We've been through this article extensively and is one of the main reasons we continue to troubleshoot because it establishes this is a supported Microsoft scenario... The exact scenario we are trying to test is outlined in table 1c

(I've attempted to upload the picture hopefully it came through)

In 1c we are expecting the following to work and it does not:

Originator Mode: TeamsOnly
Originator Client: Teams
Originator Skype for Business Homed: Online
Recipient Mode: Skype for Business with Teams Collaboration
Recipient Client: Skype
Recipient Skype for Business Homed: On-Premise

The routing shows "Skype for Business" in italics which indicates an interoperability scenario that should work, and for us right now it is not. We can initiate the IM from the on-premise homed Skype client / CSUser object to the recipient TeamsOnly mode Teams client and it DOES WORK. However the reply back does not. Both clients indicate the other client in the conversation are either in TeamsOnly mode (small purple icon in bottom left of contact when looking up on the Skype client) as well as the TeamsOnly mode CSOnlineUser using the Teams client - the Teams client shows the contact information to be on "Skype for Business and limited functionality is available"

So it works only in 1 direction, Skype to Teams and not bidirectional Teams back to Skype.... The only feedback we get is SIP error 404/1033 as I stated before something about the "Account cannot be found" and we were told to "try the full E-Mail address of the Skype contacts".... To no avail...

What could be possibly blocking the reply back to Skype? We've looked at all the ports on the firewall, in fact, tested with opening the firewall wide open and still get the error. DNS is configured correctly within Microsoft Admin Center, the CSOnlineUser objects are configured in their correct coexistence modes... real head scratcher here....

Answer 2

@JimmyYang-MSFT - I meant to reply to your last answer can you see my additional comment I made? Sorry first time using this forum, anything else you can think of regarding my latest post?