How do you talk in metal gear online

Question

As in a preset voice like "Take Cover!" or "Is it clear!"

Answer 1

You need to press select. This will bring up a box with four different options, attacking, defence, acknowledge and communication. Use the D-pad to selection which option, then you get four voice options, use the d-pad again to pick which message.

There are extra commands available, not all are put into these four by default so go to Gameplay Options for the ability to customise the commands. These voices can be expanded upon even further by buying a voice pack from the MGO store which contains more (and I think better) voice commands.  

Answer 2

Press the arrows on the controller the ones that are like up, down, left, right.