Column 2, if you like HD Voice and it's compatible with AT&T's HD Voice.
The question is whether AT&T provides good signal where you need signal. A great signal in the hallway outside your office, but a dead spot in almost the entire office (you'd be surprised) means that you can't use your phone while you're sitting at your desk, and you won't hear any incoming calls. "But the rest of the building has solid coverage." That still doesn't give you a signal where you need one. The same thing with a dead spot right around your chair in your den - you have to leave your phone on the other side of the room. (I've seen them as small as 8" diameter circles about 1" thick and as large as a suburban house. And back in the day, Nextel skipped over an entire village. Even today, in one - call it "poor town" - around here, there's almost no AT&T signal. A spot here, a spot here, but no one there can afford AT&T so they won't set up even a small cell or two. TMobile, due to the location of their tower [I'm sure it's just coincidence] covers the town like a blanket.)