The Call of Duty series games are made in IW engine by Infinity Ward. You probably would've seen the name when you start any COD series game. Almost every game shows the game engine which it is built in. The IW game engine uses c++.

Players who receive voice chat warnings or in-game voice communication penalties can still play the game. However, per the Offensive Behavior section of the Call of Duty Security and Enforcement Policy, extreme or repeated offenses may lead to a permanent suspension from playing the game online.