i am sorry i dont have an answer for you, but i am joining the discussion in hopes that someone will see this and share how to fix it. i began having the exact same problems with my iphone. i have called at&t and was on the phone for over an hour, they couldnt figure it out. when i called apple they wanted me to purchase a plan, which i am sorry but i think is ridculous that they expect all of us to pay for help. i have had nothing but problems with this phone since i got it, and unfortunaty it keeps getting worse.
so far i have
contacted and worked with at&t
updated, 3 times
turned router off and on several times, no change
turned airplan mode on and off, at least with this is will attemp a search.
still nothing, everything remains grayed out and n/a. everything else in my home, including my other phone, not apple, is fine.