So I went to a leadership training program recently, and put my SIM card(the one that came with my iPhone) into my BlackJack(from AT&T) and took that cell phone. I came pack, and popped my SIM card back into my iPhone. Everything worked fine, until today(about 1.5 days after I came back).....I looked at my iPhone, and it said "no SIM Card"...I held down the top, and "menu back" button, and it restarted, and I had service. Started listening to some music, and everything was great. Then after about two songs, I looked at my iPhone, and again it said "No SIM card"....I tried to reset it, and nothing. Still says I have no SIM card Should I just go to Apple, and get it replaced, and is anyone else having this problem?