Various cheats

12 Player Room (6 vs 6):
     At the start screen press L1, L1, L1, R1, R1, R1, R1

Unlock All Missions:
     While playing a support troop during the Cuban Operation, pause
the game and press R1, R1, R1, R1, X, Circle, L1 + L2

Turn On Voice Chat in An Online Game:
     This code must only be entered by the host. At the start screen
press R1, R1, L1, L1, R1, L1. If entered correctly you will hear a
drum sound.