Yeah, must have changed. Four years ago, different phone, same AT&T service, top of Whitney, could only get enough of a signal to make an outgoing call and get a open line (maybe), but not enough of a signal, it seems, for the open line to actually ring the phone, even though it said it was dialing and was connected -- in short, a connection with no substance, if that makes sense.
Fast forward to now, my experience is more like yours this time around -- a signal in lots of unexpected places.
CaT