The long-rumored Sprint/T-Mobile merger may soon become a reality, though details are still being hammered out by majority stakeholders Deutsche Telekom and Softbank.

Japanese news outlet Kyodo reported that Deutsche Telekom, which owns 67 percent of T-Mobile, has agreed to sell the U.S. service provider to Softbank, which hold a majority stake in Sprint.

Sources close to the situation told Reuters that no decision is imminent, but both sides are anxious to strike a deal, which would condense the number of major U.S. competitors and require regulatory approval.

Sprint and Deutsche Telekom declined to comment on the rumors; T-Mobile and Softbank, meanwhile, did not immediately respond to PCMag's request for comment.

Softbank, which paid $20.1 billion in 2012 for a 70 percent stake in Sprint, has reportedly been in talks with T-Mobile parent company Deutsche Telekom AG since late last year.

A merger, according to Softbank chairman Masayoshi Son, would help boost competition with market leaders AT&T and Verizon, which have what Son called "a virtual oligopoly," Reuters said. A Sprint/T-Mobile deal, however, would spawn a third carrier superpower that could shake up the market.

But not everyone favors the move: When rumors of the deal first emerged, PCMag lead mobile analyst and staunch opponent Sascha Segan outlined six reasons why a merger would be a bad idea.

Chief among them is the companies' incompatible networks, as well as the fact that "un-carrier" T-Mobile has excelled recently, pushing rivals like AT&T and Sprint to revamp their own plans.

The last time two major wireless carriers attempted a merge—AT&T and T-Mobile in 2011—a major fight broke out in D.C., and AT&T eventually threw in the towel following FCC and Justice Department pushback.

According to Reuters, a Sprint/T-Mobile deal strongly depends on whether DT and Softbank can persuade skeptical regulators to approve a merger.

For more, see Prepare for the Sprint/T-Mobile Merger Lies and Sprint and T-Mobile's Painful Technical Path.