If regulators saw it that way, approval might be a snap. Still, in the wake of the FCC's rejection of the T-Mobile-AT&T deal, it would be hard to predict the regulators' response, said Recon Analytics analyst Roger Entner.

"We really have no idea where they will draw the line" on consolidation among carriers, Entner said.

Consumers wouldn't see much effect from a merger for some time because of the technical work required. Both companies have emphasized low prices and they probably would continue with that pitch, according to the analysts. The combined company presumably would shift MetroPCS' CDMA subscribers toward LTE and T-Mobile's 3G network, but that could take years. Just merging the organizations internally would probably take a year from the close of the deal, Entner said.

The big payoff for T-Mobile would be additional spectrum from MetroPCS in the AWS and PCS bands, both of which T-Mobile has some of today, as well as in the prized 700MHz band, which lets carriers place their base stations farther apart.

It would probably be easier for T-Mobile and MetroPCS to bring together their disparate bands and technologies than it was for Sprint and Nextel when they merged in 2005, Entner said. MetroPCS customers are largely consumers with no term contracts, whereas Nextel's installed base was in businesses that relied on the company's push-to-talk technology, he said. Sprint is still winding down Nextel's unique iDEN network today.