It might be your phone, but it is connected to the company BES, so their rules apply. They lock things down for a reason and trying to circumvent the IT Policy could be grounds for termination.
I would not recommend trying to do what you wish to do. If you absolutely have to have your personal calendar and contacts on the device, then take it off the BES. Also remember, that nothing is personal on a BB connected to a company BES. If they want to see your activity they can.