Microsoft Lync 2010 client / XP machines connectivity with Lync 2013 Server

After a successful implementation of the Microsoft Lync 2013 we faced a problem with our legacy Windows XP machines that are still existing on the network and need to access the Lync 2013 server. This was not possible because Lync 2013 client is only supported on Windows 7 or Windows 8. The Lync Web client doesn't support all features especially the Audio/Video conference features on XP machines (Greyed out).

As a solution we tried using Lync 2010 full client on Windows XP machines. When we try to login from Lync 2010 Client in the Windows XP or even Windows 7 we received the below error.

“Microsoft Lync 2010 is not a version that can be used to sign in to the server”

 
In Order to allow backward compatibility for Lync 2010 clients on Lync 2013 server, you need to do the following:
 

1. Open Lync 2013 Control Panel
2. Click on Clients – Client Version Policy
3. Click the “Global Policy” – Edit – Show details
4. Double Click “UCCP”
5. At the bottom under Action: select “allow”  - Ok
6. Back to the Global Policy Settings Select OC Version 4.0.7.7577.4103 and allow it as previous policy (Default was block)

 The below screen shot is provided for more elaboration.

 

 



Hopefully this should be helpful for anyone facing the same problem.