You need the game in the PS3 to play it online, then it is an option available if you are also able to go online
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Call of Duty World at War, Modern Warfare, Modern Warfare 2, Black Ops, and Modern Warfare 3 all have online multiplayer.
well call of duty and modern warfare are the same it is called Call of Duty: Modern warfare and then came call of duty: modern warfare 2
Call of Duty classic Call of Duty 4 Modern Warfare Call of Duty World at War Call of Duty Modern Warfare 2 call of duty black ops call of duty modern warfare 3
"Call of Duty 6" "MW2" "Modern Warfare"
It's not available for the Modern warfare series of call of duty