With BBM, you can chat and share items in real time with your friends, family, and coworkers. You can control your contact list and decide who can add you as a contact. During a BBM chat, you can see when someone has read your message or someone is typing a reply, and you can share pictures and other files.
The first time that you open BBM, you’re prompted to sign in or create a BlackBerry ID. If you used BBM on a previous device, Make sure to sign in using the same BlackBerry ID to move your existing BBM contacts to your new device.
To use BBM, your device must be connected to a wireless network.
You can get more detail information from below link: