Bars mean nothing. My job is to develop sites for mobile phones. I have about 40 mobile phones sitting on my desk right now. As an iPhone user on ATT I can tell you that all verizon phones have superior voice by a mile. Everytime I use one of the work verizon phones (on plenty of trips) I know when I'm calling an ATT user because the voice quality is so terrible and lots of background hissing that as an ATT customer you never noticed until you get to use a verizon phone.
If you want a phone that sounds clear for calls, then get a verizon one. If you really need (a feature I've used only once, to be on a call and open a web page) then get an ATT phone.
Just realize that verizon does have a better coverage map, better voice quality (trust me, just ask any of your friends who have verizon to make a call with there phone, it reminds me of a good landline)
My point is this thread turning into a VERIZON vs. ATT thread is stupid and pointless. There both freaking Apple iPhones.
If you don't have the EXACT SAME phone on ATT and Verizon then you are not in a position to comment on the quality of service. PERIOD.
As all the reviews have stated, that the verizon was superior for voice in every SINGLE test performed.
As an ATT iPhone user, I'll keep my att iphone, but I also have a verizon iPhone on the way. Since I develop for both carriers we always optimize for network speeds, and personally i like the hotspot feature that some of the android phones have (but with terrible battery life)
So stop the fighting about verizon vs. as att. They both work equally well, they both are iphones
I'd say you're wasting your resources if you are testing against 40 different phones, when the bulk of the entire market is now iOS and Android.