Some people use a Blackberry with a data plan but without a Blackberry Data Plan.  (They aren't the same thing.)  Without a Blackberry Data Plan, you can't do an over-the-air install (because Opera mini tries to use the Blackberry Internet Browser, and the Blackberry browser won't work withou a Blackberry Data Plan). 

Here's how I installed a Java Mobile application to my 8700C.

Prerequisites:

Download BlackBerry_JDE_Components_4.2.1.exe

Here's how to get a Blackberry 8700c to work on an AT&T/Cingular account that has a data plan but not a "Blackberry Data Plan."

1. On your PC, upgrade/downgrade your Blackberry Desktop to 4.2.2.14