The 2.0.2 update made it so the iPhone did not need as high of signal in order to get and maintain a 3G connection. With so many phones attempting to get a high signal when it’s not needed, the network was overloaded, resulting in dropped calls. Well, that explains the problem, but what about those still experiencing problems?
Now it’s in the hands of iPhone users to actually download the update! With non-updated phones still trying to connect to the network, they’re still hogging the system and causing dropped calls for themselves and others. In short, update your phone, people!