The company said in a blog post that curious iOS device owners who signed up to be notified of BBM's release could begin to use the service immediately, while others would need to wait for an unspecified period of time. BlackBerry says this reservation system is designed "to ensure a smooth roll out" following infrastructure issues when an unofficial build of the app for Android leaked out last month.
BBM, originally exclusive to BlackBerry devices, works similarly to popular messaging apps like WhatsApp and Apple's iMessage service. Messages are sent via the internet using the phone's mobile data connection, allowing users to bypass relatively expensive SMS plans.
BlackBerry says group chats and broadcast messages are supported at launch. Users can also send files, photos, and voice notes using the service.
One difference between BBM and other messaging apps is that it uses special, randomized device identifiers --?known as PINs --?rather than phone numbers or other personally identifiable information to distinguish users. This makes the service essentially anonymous.
Despite BlackBerry's recent misfortune, BBM remains wildly popular, according to the company. BlackBerry said in May that the service counts more than 60 million monthly active users, with many using it up to 90 minutes per day. BBM users transmit more than 10 billion messages each day.
Bringing BBM to competing platforms was the source of major internal strife at the Canadian company, according to a report published last month by The Globe and Mail. BlackBerry co-founder Jim Balsillie reportedly pushed the strategy late in his tenure as co-CEO, and severed all ties to the company --?resigning from the board of directors and selling all of his stock in the process --?when his successor canceled the program in 2012.
Early in 2013, faced with the abject failure of the company's new BlackBerry 10-series smartphones, BlackBerry resurrected the project. The company announced BBM for a summer release, which was later pushed back to the fall.
BBM is available now as a free download from the App Store.