Blackberry have a comprehensive article here > http://docs.blackberry.com/en/smartphone_users/deliverables/43033/1196196.jsp
We would recommend the option for LAN using the BlackBerry Desktop Software.
Note this is for BES Express server. Wireless activations are generally robust against a full BES server.
Applies to:
BES Express
BlackBerry OS 7.x or less.
Does not apply to: