Dropping calls and rebooting, or the screen going black and needing to have the battery removed and reinserted before it will boot up and work again is a known problem with this model.
It would seem that the unit can use an operating system
(OS) upgrade. If you've owned this unit for a long time and have never upgraded the OS, try upgrading it to see if the problem gets resolved.
Go to your service provider's internet site...AT&T, Verizon, ROGERS, BELL etc and look for the support tab for your device...in this case BlackBerry. Surf to the model and see if they have an upgrade to the OS. You can check what your version is by clicking on the OPTIONS (wrench) icon and clicking on ABOUT. You will see the model of your device and a number following a v, ie v184.108.40.2062. If your version is older, you'll need to upgrade the device via the DESKTOP MANAGER
application that came with the unit when you bought it...or pull the application down from your service provider.
First download and install the updated version on your pc. Next, run the desktop manager application. Connect your BlackBerry via the USB cable to your pc...the desktop manager application should scan the device and notify you that the OS can be upgraded. Follow the prompts to update the OS.
Caution though. If you are not comfortable performing the upgrade, you should be able to call your service provider's customer assistance line and have them walk you through the procedure over the phone.