This is the entry level solution and will cost you <£10 more a month than your usual mobile contract (Most Blackberry contracts have this prebuilt into the contract already) With BIS you are able to forward your work emails to your Blackberry device and send and receive from that device.

If you want your calendar appointments or contacts then they will synchronise when you plug your Blackberry into your computer.

BIS is limited to push email. Calendar/Contacts/Tasks can only be done through a local sync using a usb cable. Sending and receiving email is the limit of BIS, for the full sync capabilities BES/BPS is necessary.

This is the Enterprise solution although we have implemented for as little as 3 or 4 devices and requires a Microsoft Mail server. BES licenses can cost you as much as an additional £35 / month on top of your normal monthly contract.

BES and BPS offer complete replication so, everything in your mailbox (mail, calendar, contacts, etc..) is pushed to your Blackberry and any changes, responses etc.. that you make on your Blackberry is pushed back to your mailbox.

There is also a setup cost associated with this as it requires installing a separate software product that interacts with your mail server. This does however allow you to centrally manage all your Blackberry devices. All configuration changes are done centrally and pushed out to the devices and also lost or stolen devices can be remotely disabled and wiped of all data. Managing and maintaining your companies Blackberries is made very easy with BES / BPS.

If you are looking to implement 20+ Blackberries then you should also factor in a dedicated server to support the Blackberry software.