There have been rumours in the past about Activision wanting to charge for Call of Duty online, but Activision have now stated that they will never charge for the online component in Call of Duty.
Speaking to IndustryGamers, Eric Hirshberg said "Are we going to be charging for multiplayer? The answer is no. The experience you have out of the box, connecting with the online community to play Call of Duty is absolutely integral to the experience and we'll never charge for that."
Certainly good news for consumers as many were worried this could become a reality.
Source: Industry Gamers