Blackberry Messenger is a tool that BlackBerry users can employ in order to send each other instant messages by using a PIN code. You can use Messenger for free and hold a few conversations simultaneously. Messenger can be used for group chats, too. You don't have to do much in terms of setup in order to use BlackBerry Messenger if you have a newer model; it comes preinstalled. On older models, you have to download the Messenger.
To use BlackBerry Messenger, you need to make sure your device has Java. You also need an Internet or data plan since messages travel through the Research in Motion servers. In addition, you need to know your BlackBerry PIN code. To find it, open the "Options" menu, then choose "Status" and pick "PIN." Once your software is installed, you can log on to Messenger. The first time you do, you have to pick a display name that other BlackBerry users will see when they interact with you and you have to choose a password. From then on, whenever your BlackBerry is connected to a wireless network, you'll automatically be logged in to BlackBerry Messenger. You can communicate with anyone on your contact list.
To add someone to your contact list, you have to invite him. If the person is already in your address book, you can pull him up by choosing the "Add a Contact" option from the BlackBerry Messenger menu. Then you click whoever you want to add and pick "Request." If you want to add people who aren't already in your address book, when Messenger takes you to your address book, highlight "Use Once" at the top of the list. Then pick "Request by E-mail or PIN." Put in the other person's e-mail address or PIN code and choose "Enter." Click "OK" two times. When the other person accepts your invite, he'll automatically appear on your contact list.