Blackberry OS Question:

The handheld device is used as a network device, which always connected to the data account of the user via re-director software. The software is installed on the BlackBerry Enterprise Server. The communication between the software, BE Server and the hand held devices software is always a two-way street. BES immediately updates the mobile device or the email or the calendar account, whenever a change in email account occurs.
The push technology of BlackBerry keeps the device instantly in synchronization without any effort by the user.