And it takes up a great deal less bandwidth than skype. Also, unlike LOLSTO's ingame voice chat this actually works. And works beautifully.
There's no committment to buy what so ever. Get some of your buddys on your friends list to hop on RC with you whenever you guys get a wild hair and decide to pvp. Congrats, you now have access to the single biggest tool that those ebil premades have, without spending $ each month. Solid Reliable and Rapid communication.
Installation is incredibly easy, as is setting up your servers. Joining servers is also incredibly easy. (for those of you that don't like vent cause you can't get it to work... this is so painfully easy it is almost simply point and click to join a server)
I use RC all the time, when playing starcraft2 in the teams ques (as I am strictly a pug there), Sins of a solar empire, sometimes in STO when our vent crashes and bombs out (as vent is prone to do. Never had RC do it), RIFT, wow etc.
If you have friends, (you do have friends right?) shoot them whatever your server info is, or join your buddy's server at the start of a match. If you or your friends are too lazy to setup a new server (even though it only takes like a minute tops) my RC servers are open to everyone. Alliance of Gamers and CAC Backup. Or shoot it out to team chat. Post something in Zone like "getting everyone situated on RC. 1 sec plz" so the other team doesn't just bum rush you. Most premades will not move towards the spawn if you ask them to give you a sec. If it's a pug you are against (which are the ones most likely not to listen to your request.. also funnily enough most pveers are Pugs) once everyone is situated, you'll probably start murdering them even if they are humping your spawn.
Now, once everyone is on RC, what do you do? Start by calling targets. Look for whoever you think is weakest on the enemy team, call out the target (by default IIRC Raidcall uses an open mic system which you can change to a push to talk easily). Everyone that hears it? bring your guns to bear on it. Step two, once a large amount of heals and resistances come into the target (but before they can fully repair said target ideally) call out for a sub nucleaonic beam if there's a sci on your side. Watch the hilarity ensue. If there is no Sci captains on your team, you'll have to attempt to jump targets and stay ahead of the enemy cross heals. Eventually if you are cycling targets enough, you'll find the gap between healing cool downs (assuming your enemy is smart enough to actually heal team mates) and get kills. Step three, call out for heals, and periodically give people an idea on how much longer it will be before either your best damage skills, or heals will be available.