BlackBerry's free messaging app is set for a summer debut on its rivals' platforms.

BBM is one of the reasons why, despite recent misfortunes, BlackBerry still has a firm foothold in the youth market.

The free messaging service is the ideal feature for people who can't afford large data plans and, when combined with a real QWERTY keyboard, the BlackBerry becomes the perfect smartphone for high school students. A real keyboard means that messages can be quickly and surreptitiously touch-typed.

BBM or BlackBerry Messenger, to give it its full name, supports group as well as one-to-one chats and supports image and audio as well as text messages.

"For BlackBerry, messaging and collaboration are inseparable from the mobile experience, and the time is definitely right for BBM to become a multi-platform mobile service.

"BBM has always been one of the most engaging services for BlackBerry customers, enabling them to easily connect while maintaining a valued level of personal privacy. We're excited to offer iOS and Android users the possibility to join the BBM community," said Andrew Bocking, Executive Vice President, Software Product Management and Ecosystem, at BlackBerry.

However, as good as BBM is even without a real keyboard, it is no longer unique. iPhone users have iMessage for sending free text messages, and paid apps such as WhatsApp bring the same features to both iOS and Android phones for a small initial fee.

Therefore, some will argue that BlackBerry's move, though a good one, is coming two years too late. However, by offering the app to other platforms, BlackBerry is ensuring that consumers both young and old who are tempted by BlackBerry can buy a handset, knowing that friends and family without BlackBerry devices will be able to message them free of charge.