I am unable to send any out going messages. I get an error message saying "unable to send message" whenever I try to text. I am receiving messages, but can not send. Also, this morning I received 5 or 6 text messages all at once and I am pretty sure they were sent to me yesterday. This isn't the first time I have encountered this problem... I appear to have data and signal because I can check my email and browse the web with no problem. Has anyone else run into this problem? Any advise on how to correct?