For Leagues and Clan Matches Ventrilo is required. For TDA ventrilo is not required, but is would be nice if you get it.
In case you don't have it you can download it from
www.ventrilo.comVentrilo is a team speak program that establishes better coordination between the team members. Is it much faster and easier to organize a gank or to go back by speaking it than typing it. I strongly suggest you get it.