The Blackberry Messenger allows a real time exchange of messages between two or more people who have the messenger software loaded on their Blackberry smart phones.
The way messages are transmitted when the Blackberry messenger is used differs from that of normal messengers. In most messengers, a user needs to contact the server of the messenger service provider only the first time, when they log on. The server identifies the contacts of the user who are logged in and provides their IP address; the user’s IP address is also provided to the contacts. Once this is done the server has no role to play and users chat by directly contacting each other.
In the BlackBerry messenger on the other hand, all messages sent and received are routed through servers of Research In Motion, which manufactures Blackberry phones.
These servers are always present as intermediaries when users chat. It is therefore essential to have an internet connection that allows access to the servers if a person wants to use the messenger.