I think AT&T may be having problems
When I read CptQuantum's reply - I thought AHA. I live in Washington DC and am in Bethesda daily. I have a 4S so it's not the switch between LTE and 4G that's the problem for me. For the last few weeks, my phone only rings sporadically. On Tuesday, a friend called me and when I queried why she hadn't left a message (in an email), she replied she had left 2. Those two message appeared in visual voicemail on Thursday evening. I knew it was a problem somewhere - but didn't know if it was AT&T or Verizon or what. This thread makes me think it's an AT&T problem.
Now how to get AT&T to acknowledge and fix the issues? I didn't upgrade to the 5 - as I find the off-year upgrades work for me (from 2 to 3GS to 4S). I bought a iPad mini on Verizon, but haven't used the cellular data yet (I really bought it for GPS chip), but haven't liked some of the things I've heard on these boards about Verizon. However, now I am wondering what I will do next year when the 5S or whatever is released. Verizon is supposedly better in the Washington DC area because of the frequencies they operate on, and the server problems on AT&T have really gone on too long, as well as the call fail rate. (I have many each time I try to call on my drive from Bethesda to DC.) I should call and complain again, but ...