How to Determine What Version of LCS or OCS You Have Installed

Here's an easy way to figure out exactly what version of LCS or OCS you have installed.

For LCS or OCS, check the following key:
HKLM\Software\Microsoft\Real-Time Communications\{92AC8981-AAD9-4391-8563-92E558EEF4C6}

For OCS 2007 R2, check the following key:
HKLM\Software\Microsoft\Real-Time Communications\{A593FD00-64F1-4288-A6F4-E699ED9DCA35}

Possible Values:

Server
SE - Standard Edition
EE - Enterprise Edition

Type
Volume - Volume License Edition
Eval - Evaluation Edition
MSDN - MSDN Edition

Version
2.0.5369.0 - Live Communications Server 2005 RTM
2.0.5470.0 - Live Communications Server 2005 SP1
3.0.6362.0 - Office Communications Server 2007 RTM
3.5.6907.0 - Office Communications Server 2007 R2 RTM