The problem with Voice over IP is that it's very bandwith demanding, meaning that if too many people start yapping, usually the pipe from the server just crumbles and dies. Not to mention that the server itself gets a much larger overhead trying to route all those signals, and since I doubt that Sony has spent any kind of money on hardware / bandwith upgrades since that Voice over IP went in, it's not too hard to see where their problems are coming from.
Quite frankly, unless you have a big fat connection, I doubt you're going to have a very appealing gameplay session if you try to run something as data intensive as a MMOFPS AND try to combine it with voice over ip...
Ahhh the future, how bright you look.
Creston