Are there voice Commands on Call Of Duty 4 Modern Warfare?

It depends what console you're on. Say if you're on the Xbox360 or PlayStation3, you can just talk to other people by a microphone. I think it's the same for the PC version. If I was you, just look at the game booklet for absoloute detail and if you're still not sure, ring the creators; but it's not like you're going to do that... ;)