Update on a 4S

I still have a 4S and I completed the recent update. I cannot make or receive calls now. Everything else works fine. What can I do? I hope to get a new phone, but I'm afraid they won't trade now, saying the phone is damaged. The phone was fine before, so if I can remove this software, please send me info on how to complete that service. Please advise, if you can. Thanks for listening!