ok, i've gotten used to the occasional dropped call ever since I got an iphone 4 this xmas, but i'm having a serious issue now that i've never experienced before.. i've been sitting here trying to make a call to somebody, anybody, for about an hour, and it has consistently given me call failed errors before i even hear a ring. outside or inside same thing happens. i restarted my phone, same thing. i had someone call me instead, which worked, but after that i still can't make a call! has anyone had this happen before? any clue what might be going on? my bill is paid.