And how is VOIP gonna be better then Karma, which isnt perfect either while we dont even know how it will work? People will just pretend either way to be friendly and shoot anyone they want in the back. VOIP itself is cool and I also wish it to be implemented. BUT I dont think it is gonna do anything to fix the current problem of everyone killing everyone.
As many people allready do, best solution is either play with friends over ts/discord/skype w/e there is OR find a group/can to play with. No need for Karma. Scavs are made egocentric anyway. (While it would be much more profitable to play togather to kill the PMCs but people have too much poo in their head I guess). PMCs , as seen in the trailer, can even befriend between factions.