Samsung has today announced that its cross-platform ChatON messaging service now boasts over 100 million users across Android, BlackBerry, iOS, and Windows Phone. It’s taken just two years for the service to become more popular than BBM, once one of the biggest names in instant messaging, and it continues to grow at an impressive rate.

Over half of those 100 million users signed up for ChatON in the past four months, Samsung says, and it’s all thanks to its support for multiple platforms.

“The service provides a seamless experience where users can access ChatON through PCs, Samsung feature phones, and all the major smart phone operating systems: Android, iOS, BlackBerry and Windows Phone,” the South Korean smartphone maker said.

With 100 million users, ChatON now has around 25 million more users than BBM, but it has a long way to go before it catches up with other popular cross-platform messaging services. Viber reached 200 million users back in May, which is roughly the same number of users boasted by Line, while WhatsApp now serves more than 300 million users.

Samsung isn’t quite counting its user base in the same way as some of the others, however.

While services like WhatsApp count the number of active users that sign in and take advantage of its service every day, Samsung is simply counting the number of users who have registered for ChatON — so there’s likely a certain percentage of those 100 million people who no longer use the service.

Nevertheless, it’s an impressive number of users in a market that offers some stiff competition, and it’s only going to get tougher. We’re still impatiently waiting for BBM to launch on Android and iOS, and when it does, it’s likely that will see a sharp increase in users, too.

• ViaCNET