That forthcoming rollout of the Long-Term Evolution (LTE) technology was the other major potential benefit of the deal touted by AT&T. This 4G wireless network should allow for faster data speeds and improved capacity, though AT&T cautioned that full deployment is still some time off. In that race, the carrier is playing catch-up to Verizon, which . AT&T has that it plans to begin a migration to LTE this year. With the addition of T-Mobile's cell sites, AT&T says its LTE network will be able to reach 95 percent of the U.S. population.

While the timeline for LTE adoption still makes it unlikely that Apple will produce a 4G iPhone this year, the T-Mobile/AT&T merge may, once approved, speed the technology's rollout, making a 4G iPhone possible sooner rather than later.

The merger "should speed up the rollout of LTE, and [AT&T should] have much greater LTE coverage," said Tim Bajarin, president of industry analysis firm Creative Strategies. "In theory, once you go to LTE networks, you should have better-quality calls and less dropped calls. But all that's theoretical, since we don't have those networks yet."