Sooooo annoying! This has been going on, off and on for the past month. I will randomly be having a conversation through text message with someone, and then it will suddenly stop. I have 4 bars, I can make phone calls, go on the internet and do everything else just fine. But i can't send texts messages, even though I can get them from people. And then, it will just start working again. Then a little bit later it will act up again. I have tried restarting my device, shutting it off and taking out the sim card. Nothing fixes it. It only starts working when it decides it wants to haha. Its getting very frustrating though!