As promised, AT&T—jointly with T-Mobile and Deutsche Telekom—has filed its response to last week's lawsuit blocking its proposed merger with T-Mobile. The Department of Justice laid out its concerns over reduced competition, but AT&T "vigorously contests" those presumptions, arguing the merger is in fact "good for consumers."

AT&T announced that it planned to acquire T-Mobile from its German parent Deutsche Telekom for $39 billion in March. Unsurprisingly, the deal drew attention from the Senate antitrust committee, with Senator Al Franken (D-MN) calling the deal "unfixable." AT&T countered, claiming T-Mobile wasn't a significant competitor and didn't have a compelling portfolio of advanced wireless devices. The merger would effectively improve AT&T's network without removing competition from the marketplace, the company said.

There was a lot of skepticism about AT&T's arguments, including on the part of the DoJ. Last week, it filed a lawsuit to block the merger, citing violation of antitrust law. "AT&T’s elimination of T-Mobile as an independent, low-priced rival would remove a significant competitive force from the market," the DoJ said in its complaint.

AT&T opposes this view, suggesting that the DoJ has no proof that this is true. In fact, the company's formal response claims, the deal is actually a boon to consumers.

"The new network will be more than the sum of its parts: as a result of engineering efficiencies enabled by the transaction, the combined capacity of the new firm will be significantly greater than what the two companies could do separately," according to the response filed on Friday in federal court. "That means increased output, higher quality service, fewer dropped calls, and lower prices to consumers than without the merger. Rather than substantially reducing competition, the combined firm will usher in more intense competition to an already vibrantly competitive market."

AT&T and the DoJ will have their first courtroom encounter next month in Washington, DC.