I need help with my iPhone 4. It was working fine till Last week. Now my iPhone – Can't receive SMS or send SMS. – Can only receive and send SMS via iMessage. – Can't receive calls or send calls BUT when I try to call it ends the call and a message appears "call ending". I'm not sure if this is a network problem or a phone problem. I've tried turning it off and on, resetting my network connection, etc. but the problem persists.