BlackBerry finally released BBM for iOS and Android after a botched release in September 21st, 2013 for Android release and iPhone release on September 22nd, 2013.
During its phased rollout, users need to enter their email address to have themselves included in the virtual queue. Users that registered their email before the initial release can use BBM instantly.
BlackBerry is still concerned about an initial surge of users. It's implementing a registration wait list; upon opening the app, users have to enter an email address to reserve their place. Anyone that signed up for information about the mobile apps at BBM.com won't have to wait, but new signups will have to deal with the virtual queue.
"We are focused on moving millions of customers through the line as fast as possible," BlackBerry says. The company will be providing updates on "how quickly the line is moving" via its Twitter account.