The Blackberry Network
http://www.cnbc.com/id/41890557/Blackberry_Game_Changer_BBM_Coming_to_iPhone_Android
One of the main reasons people buy Blackberrys is to use Blackberry Messenger(BBM). BBM is an instant messenger application that allows for quick messaging between Blackberry users. Most cell phones deliver text messages through Short Message Service(SMS). Unlike SMS, BBM only users with Blackberry phones can communicate via BBM. BBM on its own creates a separate network for blackberry users, along with the default SMS. BBM allows for the user to have a friends list, update pictures, and update statuses; similar to facebook. It is also much faster than SMS, and provides excellent delivery notification that shows when your message was delivered and read.
The BBM network is faster than SMS because messages are sent through its own server. There are much less people on the BBM network compared to the SMS network since BBM is strictly for blackberry users. If you think of a graph, the amount of nodes in the graph are much less than that of the SMS network, so there is less delay or backup in messaging. Also friend lists create separate networks per user. Each node has its own group of nodes that it is connected to so it is easier to find these other nodes and send messages through each path.
Due to the efficiency and popularity of BBM, other smartphones, like androids and Iphones, have been trying to implement a messenger app similar to BBM. WhatsApp messenger and Kik are similar instant messenger apps that can be used by all smartphones, and there is also rumors that BBM may come to Androids and Iphones which may decrease the popularity in Blackberrys.