BE AWARE prox chat, and always-on audio chat, is a very serious drain on netcode sources (it causes lag, potentially a lot of it), in fireteams you can set aside bandwidth for the other people in your fireteam, forming a "tight link", that isnt as resource intensive.... think of it like having to start and end a skype call every time a player gets within range or moves out of range. lots of picking up and hanging up.