I recently used my old iPhone 4S for the first time in over a year (it was unplugged and dead all of that time). It still has iOS 6.1.3. After charging it and using it for over an hour, the top-left corner says "Searching... 4G" instead of "[bars] AT&T 4G." The service for this phone was continually paid for throughout the period in which it wasn't used. It does have phone service (and internet via the cellular network), but had a mere 1 voicemail waiting for me, and it was from 2 days ago. There were no new text messages, and I know I have been sent many. It did later successfully receive a new text as part of a security process for my email account. My Facebook notifications aren't listed either. Why isn't my carrier (AT&T) listed, and where are my text messages and voicemails?