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Video Call Federation with Microsoft Lync to Windows Live Network

Filed under Lync

I was recently troubleshooting an issue where Lync clients could not connect via video calls with Windows Live Messenger 2011 clients. The users could instant message each other but video calls would never connect.

The underlining issue for the disconnect is that Lync requires SRTP encryption by default which the Windows Live network does not support.

Assuming that your federation is working to the Windows Live network, we have to insure that the Lync users have Public A/V connectivity:

Set-CsExternalAccessPolicy Global -EnablePublicCloudAudioVideoAccess $true

 

The second step is to change the Lync encryption requirement fromt required to supported. The Lync client will still try to negotiate an encrypted session first, but if that fails it will allow the unencrypted session with the Windows Live network to take place:

Set-CsMediaConfiguration Global -EncryptionLevel SupportEncryption

 

You can also apply these commands to a specific policy that you have created. After these commands are entered on the server, wait a few minutes and then sign out and back in to the Lync client. You can verify that change has taken place by looking at the PC to PC AV Encryption in Lync (hold down CTRL and right click the tray icon and select “Configuration Information”. The setting should display “AV Encryption Supported”.

If the encryption level is not changed there will be an error logged on the Front-End server when an A/V call is trying to be established:

Start-Line: SIP/2.0 488 Not Acceptable Here
ms-client-diagnostics: 52017;reason="Encryption levels do not match"
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