The headset is in no way required to play the game. You may sacrifice a small tactical advantage in that you can't communicate to your teammates, but it really isn't a big deal. Most people are just annoying or just socializing, I mute everyone unless I'm playing with friends.
Your phone can not be used to provide PS3 internet or as a headset
No
I think you can't.
Yes
System Link
Yes, there is online multiplayer on Call of Duty 4: Modern Warfare.
there is none
No, Call of Duty: Modern Warfare 3 for Wii is single player.
no but your just going to have to look on modern warfare 2 online
Jtags
You cant!!!!!!!!!!!
Call of Duty World at War, Modern Warfare, Modern Warfare 2, Black Ops, and Modern Warfare 3 all have online multiplayer.