I've had my iPhone 4s for almost two months (I got it from a friend). It's been working fine up until a few days ago. On Saturday, I was suddenly not able to send or receive texts, but I could make and receive calls. I reset my phone and tried a dozen suggestions, but with no luck. A little over an hour later, I received all my texts from the previous hour.
This morning, the same thing happened. This time, however, I couldn't send or receive texts or calls. I have reset my phone, reinserted the sim card, cleared the network settings, and let my phone stay off for a bit, but there is no change. If I try to make a call, I hear three beeps and the call is ended. When people try to call me, the call just drops. I'm open to any suggestion at this point.