I went to AT&T today they were flooded with customers coming in for the same reason. They ran the latest update and after they ran the update their phones stopped working!
Yesterday I was on the phone with AT&T for quite some time because of a PUK problem which they fixed but my phone still had problems, so I called Apple who logged into my phone. He thought he had resolved the problem and wanted me to reset my network. Well, that made the problem worse.
Today I went into my service provider and found that I wasn’t the only person with this same problem, there were several other people waiting to have their phones looked at because they had run the latest update.