BlackBerry has officially announced that its BlackBerry Messenger (BBM) app will become available for iOS and Android this weekend, on Sept. 21.

The company's BBM messaging system has gained a lot of popularity over the years, but it was only available to BlackBerry users. As the BlackBerry platform lost significant ground to iOS and Android rivals, many users switched to those platforms but still wished they had the BBM.

"That's right BBM fans - the iconic mobile social network will begin rolling out for Android and iPhone customers around the world from Sept. 21," the company announced in a post on the BlackBerry blog. "Soon, you'll be able to easily connect with friends on different platforms. As you may know BBM was previously exclusive to BlackBerry smartphones, and it will be available as a free download in the Google Play and the App Store."

The BBM for Android app will become available on Sept. 21, while BBM for iOS will arrive one day later, on Sept. 22. The BBM apps for Android and iOS, however, will not have all of the features the app has on BlackBerry smartphones. As expected, BlackBerry still kept some features exclusive to its platform so it could attract more customers to its latest BlackBerry 10 OS.

The BBM apps for Android and iOS will still sport popular features, including BBM Chat, group conversations, unique BBM pin pass-codes, or the ability to send files. Voice and video calling via BBM, meanwhile, are among the features that will remain exclusive to BlackBerry devices.

According to the company, BlackBerry has about 60 million customers, most of whom use BBM for roughly 90 minutes per day, on average.

"BBM is a very engaging messaging service that is simple to use, easy to personalize and has an immediacy that is necessary for mobile communications," said Andrew Bocking, BlackBerry Executive Vice President for BBM, in the press release. "With more than a billion Android, iOS and BlackBerry smartphones in the market, and no dominant mobile messaging platform, this is absolutely the right time to bring BBM to Android and iPhone customers."

The BBM apps for Android and iOS will become available for download this weekend from the Google Play and iTunes Store, respectively. Supported platforms include Android 4.0 and above, iOS 6 and iOS 7.