My phone keeps dropping calls. It happens several times a day and is getting annoying. After the call drops I would look at the screen and it says searching where the signal bar is. Then it picks up a signal and I can call again. Another thing is if someone calls me and it drops the call I go to recent call log and there is no record of receiving that call. I have done a reset and taken it to Apple and they plugged in to their laptops and reinstalled software. I thought this may have fixed it but I still get dropped calls but now if the call drops the screen just goes black. Any ideas on what it could be. Don't really want to buy a new phone.