In Lync 2010 when enabling users for “Enterprise Voice” you would get the Audio Selection Menu which helped you select your primary device at any time. This was an important menu since it would let you know what was your active device at any given time and was a huge improvement over the Communicator 2007 R2 clients. Originally it was intended that this menu was going to be enabled for users enabled for “PC-to-PC only” as well, but it ended up being a bug that became a feature.
Now in Lync 2013 the ability to select your primary device is available for any user enabled with “PC-to-PC only” or “Enterprise Voice”. This totally makes sence since a good audio call is important for users that uses Lync for Lync to Lync calls as well and selecting the correct audio device is crucial to the success of Lync.
Note: The menu is disabled for users enabled for “Audio\Video disabled”, “Remote call control” and “Remote call control only”