A game that is great to play in squads and with teamspeak is America's Army ( a free tactical military shooter developed by the US Army), the 3.0 should be out within the end of the year and will be written from the ground up using the Unreal Engine 3.
Now it is at 2.8.3.1 and it's still based on Unreal Engine 2, and it shows its age compared to CoD4 graphics wise.
But gameplay is totally different (no respawn, timed rounds with objectives, most of the time you use 1 maybe 2 clips in a whole round, unless you spam).
It's all based on teamwork (if you want to do Rambo you better be they-call-you-haxor good), cover and sneakyness is essential.
Since it's free you could give it a try, be warned it can be frustrating at first when you get owned in the first 30 seconds and then have to wait 5 minutes to play other 30 seconds.
