According to recent comments made to Eurogamer
by Infinity Ward producer, Mark Rubin, upwards of 1.2 and 1.3 million users are consistently
logging on to Call of Duty 4 on Xbox Live, worldwide, every day of the week. To top this, according to Rubin, the PS3 and PC numbers are even higher.
"There's even more on the other platforms [PS3 and PC], but we just don't have the same numbering system. Overall, even without the other consoles, we are beating the competition. PS3 numbers are monstrously huge. No other game has come close, either online current, or total unique users in a day," he told the site.
For a while it was neck and neck on Microsoft's service between Halo 3 and Call of Duty 4, but over the past few months the Activision published shooter has pulled incredibly far ahead of the pack. This growth is bound to continue on all formats even more so as Infinity Ward are gearing up to released a map update for the game.