The game does not support voice chat built-in, but GSC which we included with the game works great. It even supports both of our newer games so you can launch a game from within the LAUNCH menu.
So we figured, why re-invent the wheel?
The GSC installer is included with the game. Just run the GSCsetup.exe program located in the Steam game install folder or use the shortcut located in START/PROGRAMS/3000AD/ALL ASPECT WARFARE if one exists. Or you can download it from http://www.getgsc.com
We recommend GSC because it is very simple to setup and use. Plus you can create private voice servers for your group if you want to. All of it much simpler than Ventrilo and Teamspeak.
Since it also has built-in IM chat (which works inside the game as well, just like the Steam overlay), you can also use that instead of the game's built-in chat if you so choose.
Anyway, the procedure is as follows
Install GSC. Then go to Help and "Check For Updates"
Run GSC and setup it up to use your microphone.
If you are using PTT (Push To Talk) - which is recommended - make sure to bind the key to one not already used by the game. I use the ` (tilde) key.
Go to the VOICE tab and press +ADD, select BY SEARCHING. Then type in 3000AD and press SEARCH to show the 200 person public voice servers we have setup.
Pick one or both of the detected servers and choose ADD SELECTED TO in order to add to your quick list
Join the designed voice chat server
Launch the game
With the servers added to your quick list, you can now join the voice server prior to joining a game server.
