VoIP can be something good if it's usefull for gameplay, nothing else.
I don't want one absolutly realistic, with the possibility to ear or not your team mate. Coz if we want to be realistic wich a such VoIP, why not be able to communicate by sign of our hands and by the way how many keys I will have to configure that ?
If we will play 20x20 or a coop with 40 players, will be cool that only group leader can speak on two channels (just 2 keys to configure on keyboard). One channel for their own group, and one for coordinate actions with the others group leaders. I would like to use a such VoIP, simple and usefull.