XCOM: Enemy Unknown - Disable Voice Chat in Multiplayer

1. Go to your My Documents folder.
2. From here, go to: My Games\XCOM - Enemy Unknown\XComGame\Config
3. Open the "XComEngine.ini" file.
4. Press Ctrl+F to search the text.
5. Type in "VoIP" and press Enter to take you to the right part of the file.
6. Change the following line:
   bHasVoiceEnabled=true to bHasVoiceEnabled=false
7. Save the file and close it.