The $26 billion T-Mobile Sprint merger, which cleared one of the last hurdles for approval Tuesday, includes several pledges to keep regulators happy — but the unification of two of the four largest phone service providers in the U.S. leaves some questions for consumers.

T-Mobile promised phone bills will remain the same for the next three years, and the Federal Communications Commission noted as much when it approved the deal last year. However, not everyone is convinced, given that the company must improve profitability for its shareholders.

“Over and over again, consumers are promised enormous benefits and so-called ‘efficiencies’ by merging parties,” said former FCC commissioner Gigi Sohn, a fellow at the Georgetown Law Institute. “But what they are left with each time are corporate behemoths who can raise prices at will, use their gatekeeper power to destroy competition and new voices, and hijack regulatory and legislative processes. We are already seeing this with the AT&T-Time Warner merger, where promises not to discriminate against rivals or raise prices were broken within months of being approved by a trial judge.”

More at NBC News.