There is a different way of getting email and calendar items from an exchange server except the known BES method which enforces the organization to install the blackberry exchange manager software on the exchange 2003, exchange 2007 and exchange 2010 server.
This kind of connection can be done as follow:
1.Press the bear paw icon (known as Blackberry icon)
2.Go to Setup.
3.In Setup menu < go to email settings.
4.You should see a list of all email accounts configured in your Blackbery (those are only the non-enterprise emails as BES email configured under "enterprise activation")
5.Click "Add" to add to add Yahoo, AOL, Gmail, windows live accounts.
6.Press "other" to add new email account (even Microsoft exchange mailbox).
7.Type your email address and password and you’re done. Blackberry will automatically identify the outlook web access URL over the network.
8.To change the OWA address or other settings (like filters, timeout, sync options etc) by clicking the operation button while marking the requested account under "email settings" < choose "edit" < choose "advanced options" < change "Outlook web access URL"
9.To change the signature of email getting send by this device trough the OWA account, go to "email settings" < choose "edit"< choose "general options" <set the signature text.