i get this question a lot now days
"my team can't communicate worth tits on a boar hog. we always make wrong calls on the amount of enemy's we see. and we always end up going to the wrong bomb site and we over rotate almost always resulting in us losing the round because
we didn't defuse the bomb in time."
First off you should show your team the "proper" way to make calls. In my opinion the best way to make calls is to be as specific as possible where possible. well use the map de_dust2 for an example, if I hear a rush on cat I'll immediately count in my head how many I hear. If I know it is more than two people I hear rushing, I will say "at least three rushing cat." If four guys come around the corner I would say "four guys." If one or more of those guys has a deagle I'll say "some have deagles." If I'm on vent and I'm able to freely talk after I'm dead (don't try to do this at most LANs), I'll try to call the direction the players are running accurately. Like, "three top A one going back cat." If I'm not sure, just add "three top A, I THINK one going back cat." If I'm rotating over to top A from long to take the site back on dust2 if I see anyone by greenboxes I'll immediately call "at least one green boxes," or "one green boxes." The more accurate you can be the better.
If I get killed in an area where I'm alone, after I die I'll immediately call what he is doing "might be running back," or "he's walking up." And then I'll call "just one so far" if it was only one guy.
Getting people to make the proper calls is a big part of communication. Make sure everyone is calling in the best way possible. Whenever you can, try not to say "some B," for example. Try to be specific, because calls like "some B" can lead to premature rotation, where as a call like "at least two B, one spamming" is a lot more helpful.
I think the best thing you can do to get people talking more, is show them an effective way to call. You can also take it a step further, and make it so everyone can only use in-game mic chat which means they have to become adept at making a call while or before they initiate the fight, or run the risk of not helping the team at all