A Blackberry communicates with the BES through an encrypted tunnel. The RIM Operations Centre acts like a switchboard allowing the Blackberry to establish that connection from any wireless carrier anywhere (that supports Blackberry). The power in the system is that it also allows the BES to establish a connection to the Blackberry on any wireless carrier anywhere (that supports Blackberry). This means that the Blackberry doesn't have to maintain a connection to the server so that the server can push data to the Blackberry.

It is a powerful and beautiful thing.