TeamSpeak and Roger Wilco are scalable Voice over IP (VoIP) communications systems that allow users over the internet to talk to each other, in real time. You and your teammates can use them to coordinate your next rush, plot your next attack, or share recipes for excellent fudge brownies.
Specially trained pixies watch over your voice as it travels through the intarweb, making sure that your voice reaches your teammate's ears quickly and clearly. It's that good! (Actually, pixies don't exist. Even if they did, and we had control over them, they wouldn't be routing voices over the internet.)
Currently, we charge $2/person for a public and $1/person for a private server. Unfortunately, we can't guarantee that having a voice server will help you play better. Last time we played with one, we got absolutely owned.
Your mileage may vary.