BlackBerry has rolled out BBM—BlackBerry Messenger—for Android and iOS “again”, today. This time around, they are making it available in stages and they are giving preference to those who signified interest in getting update about the availability of the app.
If you head over to BBM.com with your Android or iOS device from your mobile browser, you will be able to download the app as long as it is available for your region. Once you download the app, you’ll need to enter your email to reserve a space or get in right away if you had initially reserved a space.
BlackBerry has this to say:

“BBM Roll Out Details:

Download BBM – the easiest way is to visit BBM.com from your Android or iPhone browser*
Once you install the app, open it, and enter your email address to hold your spot in line
We will email you as soon as you reach the front of the line and can start using BBM

If you are among the millions that took the time to sign up at BBM.com, you can start using BBM immediately without waiting in line. If you didn’t sign up in advance, don’t worry – we are focused on moving millions of customers through the line as fast as possible.
According to BlackBerry, In Sub-Saharan Africa, BlackBerry is in partnership with Samsung. BBM won’t be available to iPhone and Android users in Africa right away. Only those having a Samsung Android phone that is Android 4.0 and above can get the BBM app using the Samsung Application Store.
to see how this is done click here:http://teewodavie..com/2013/10/how-to-get-bbm-for-your-iphone-and.html