SYNC A707 will not make or receive calls...

I used my phone this morning....calls and receiving and sending text messages. I received a text and when I replied and hit send it would not send. I have a full signal and when I try to make calls it sits there, then just ends the call. When someone calls me, they get the phone ringing and my voice mail, but my phone will not ring. All the other phones in my family plan are working fine, and my acct is up to date. SIM card works in another phone. I have turned it off and on, I have removed the battery and reinserted....any suggestions? Phone is almost 1 year old.