My iphone 3gs wont get service ANYWHERE!!!!?

I normally get great service but the last few days it will not get service but one small place near work. I have been all over South jersey and cant get service. I have tried rebooting it. toggling airplane mode. toggling 3g. and I even reset the network settings. Nothing works. Oh and I removed and put back in the sim card and nothing work. PLEASE HELP ME!!!!!!!!!!!!