mherm7, I'm solely speaking from a past experience here. My buddy had a 4s and his device did the same thing after just under 13 months of owning it. e.g. about 25-30 days outside of this 1-year warranty. He setup a appt at the Apple Store. Within 2 mins or arriving and speaking to the Apple employee they simply said there is nothing they can do to fix it and he "needed to get a new phone." This is the only time I've personally heard of this issue. His was greyed out and could not be toggled on. Since and an iPhone 5s I'm guessing it is out of warranty. If you have AppleCare I'd def setup an appt and take it to Apple. It maybe worth a shot to still try it. I'm guessing they are doing to suggest:
Reset Network Settings, backup the device and restore to vanilla to try it, etc.
Let us know the outcome. I'm curious to what Apple says. Lastly, if you have insurance etc. that is an option more than likely. Or you could always trade it in.