BlackBerry Enterprise Server (BES) is the software platform for BlackBerry aimed towards business usage. You can connect your BlackBerry to a BES server running Microsoft Exchange, or Lotus Domino, among others, to synchronize contacts, emails and other BlackBerry features. BlackBerry Internet Service (BIS) is the personal, non-business, platform for BlackBerry to access the Internet and email. Both BES and BIS can be installed simultaneously. If you have been using BES, then you have to additionally set up BIS for personal, non-Enterprise usage.
Contact your phone carrier and set up a “BlackBerry Internet Service” plan.
Go to your carrier’s BIS website (a list of is provided in Resources below via BlackBerry FAQs, click your continent to be redirected to the BlackBerry.com page, then click your carrier’s link at the bottom of the page).