Up until CoD MW2 the game had dedicated game servers for MP.
CoD 4: MW, released 2007, was actually a great game. Dedicated servers you could customize the game to your liking with.
CoD: MW2 (2009) killed the franchise. What fascinates me the most about the franchise is that it went for 15 years, getting shittier yet more successful with every interation, until recently.