"Being really early, six months into it, I would tell you we're more enthusiastic today than we were when we first started it," he told CNBC's "Squawk Box" at the World Economic Forum in Davos, Switzerland.
AT&T recently announced it would reinstate unlimited data for customers who subscribe to its U-Verse television plans or DirecTV's satellite TV service. AT&T closed its deal to purchase DirecTV for $49 billion in July.
To support the new unlimited plans, AT&T will bring a large block of spectrum to market that currently hosts no traffic, Stephenson said. He said AT&T is in a unique position thanks to its portfolio of infrastructure — including satellite, fiber optics and wireless — to deliver data.
AT&T was able to offer unlimited data — a proposition that other carriers have dropped or limited — because it began building up its portfolio of spectrum needed to carry that data years ago in anticipation of its current strategy.