Mat8754, Oct 30, 2014 : I recently factory reset my phone and ever since I have had issues with phone calls. I have ATT and when I am on LTE after the phone rings several times the call drops and I get the hang up beeps. Sometimes it connects for a few seconds and then hangs up. When I look at the service bars it goes down to zero and then quickly back to full. When I switch the setting to prefer 3g over LTE the calls work fine. I seem to only have this issue when the phone is set to prefer LTE network. I never used to have to this problem so any help would be greatly appreciated thanks!