Dropped calls, idk but OtterBox cases can be rolled over with a car. Even a generic case can be good. I got my teacher a $15 boring black case and he forgot it on the top of his car at 5AM and hr drove away and it smashed and the case kept it together. The cases keep the phone, but the screens do crack easily.
My iPhone 4 has one and I've dropped it and I've sat on it an stepped on it and it's fine. it's also an awesome shade of pink.
Otterbox deffinetly !!! I dropped my phone alot and had no problems with the phone at all !!! Just watch where ya clip it on your pants, it's kinda big so it's easy to knock it out of the clip if ya get too close to stuff. But the case does protect it really well !!!!