With its first effort to make BlackBerry Messenger available to users of Android and iPhone foiled by technical issues, BlackBerry is taking another run at making the service cross-platform. On Monday afternoon, the company said BBM will soon be available on the world’s leading mobile platforms. But folks who want it may have to wait a bit. To avoid any further cock-ups, BlackBerry is managing the service’s rollout with a registration queue. In order to use the service, you must first download the app and reserve a spot in line by registering with an email address. When you reach the head of the queue, BlackBerry will activate your account and send you a notification. According to BlackBerry, six million people have signed up for information about the launch since September. “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,” the company said in a blog post.