Once again it appears a T-Mobile and Sprint deal is on the table.

Sources told CNBC both carriers and their parents, Deutsche Telekom and Softbank, are in active talks about a stock-for-stock merger, with T-Mobile parent Deutsche Telekom emerging as the majority owner.

Back in May, Softbank CEO Masayoshi Son indicated T-Mobile was his top choice for a Sprint M&A deal, saying the Un-carrier was the most obvious choice in terms of synergy and remained the “first priority” for merger talks. Though at the time, he also acknowledged a deal would likely come with a fair amount of baggage, and was thus keeping options open.

According to CNBC, T-Mobile CEO John Legere would be expected to lead any combination that comes from a deal, though Son would want a say in how the company is run.

T-Mobile has reportedly not started due diligence on Sprint yet and a deal is still weeks away from being finalized, according to CNBC.

In August MoffettNathanson analysts examined a Sprint-T-Mobile deal and contended that while there are great challenges, including the regulatory hurdle of approval from the U.S. Department of Justice, that the potential synergies from a deal made it compelling enough for the two carriers to at least try.

“That said, the integration costs of achieving those synergies are also enormous, and likely far higher than most anticipate. These costs would push out FCF benefits much further than people think,” the analysts noted. “And that’s a problem, as the two companies already carry an unhealthy amount of debt.”

“Still the synergies are large enough that we continue to believe that at least an attempted merger is a matter of when, not if,” MoffettNathanson analysts observed.