The Federal Communications Commission has re-started the clock on its review of the AT&T and T-Mobile merger. The agency's review of the controversial merger now continues, but there's no word on when it will issue its recommendations on the deal.

In reviewing mergers, the FCC follows an informal 180-day clock to keep itself on track. The agency is not required to rule on mergers within those 180 days, but it generally aims to have things done before that clock runs out.

In July, AT&T informed the FCC that it would submit new models by which it would measure the effectiveness and benefits of a merger with T-Mobile. As a result, the FCC stopped the 180-day clock until AT&T turned in those new models.

The carrier did so and on August 11, the FCC sent AT&T a list of questions for further clarification. The commission said it has also had several meetings with AT&T about the updated models.

"We have now received AT&T's answers to our specific questions as well as AT&T's confirmation that it believes our record is complete with respect to the models," Rick Kaplan, the chief of the FCC's wireless bureau, wrote in a Friday letter to AT&T.

At this point, AT&T is not expected to submit any additional documentation, and as long as it sticks to that plan, the clock is restarted. "As such, today, August 26, 2011, is Day 83 under the time clock," Kaplan wrote.

"We are pleased that the FCC has restarted the clock and we are confident that the Commission will move expeditiously to complete its review of our merger with T-Mobile," Bob Quinn, AT&T's senior vice president of federal regulatory issues, said in a statement. "The engineering and economic models we have provided the Commission confirm the extensive capacity gains and corresponding consumer benefits that the combination of AT&T's and T-Mobile's complementary assets will produce. Once approved, this merger will unleash billions of dollars in badly needed investment and will create many thousands of well-paying jobs."

Those who opposed the merger, like rival Sprint, viewed AT&T's new models as the carrier grasping at straws. AT&T is basically acknowledging that its first argument holds no weight so it's throwing it out and coming up with another one, they said.

"With today's decision to re-initiate the 'shot-clock,' the FCC will continue their work of evaluating whether the proposed takeover is in the public interest. We are happy with this action, as it halts AT&Ts on-going attempts to redefine its justification for this acquisition and will allow the FCC to move quickly to reject the application," Vonya B. McCann, Sprint's senior vice president for government affairs, said in a statement. "As the record shows, the proposed takeover of T-Mobile would push the industry into a duopoly where innovation would be stifled, jobs would be lost, competition would be strangled, and ultimately, consumers lose."

"We're glad the FCC won't be giving AT&T a fifth shot at manipulating its economic model. No matter how many tries AT&T gets, however, nothing can change the fact that the case for this merger is unraveling," S. Derek Turner, research director at Free Press, said in a statement.

The Department of Justice is also reviewing the merger, which was announced in late March. In recent months, members of Congress like Sens. Herb Kohl and Al Franken have encouraged the agencies to reject the deal, while Rep. Lamar Smith said the agencies shouldn't base their decisions solely on Congress.

For more, see PCMag mobile analyst Sascha Segan's letter to the FCC about the merger as well as 10 Big Questions About the AT&T/T-Mobile Merger and AT&T Buys T-Mobile: Great For Them, Bad For You. Also check out the Five Best T-Mobile Features AT&T Must Keep slideshow below.

Editor's Note: This story was updated Friday night with Sprint's statement.