The FCC Republican majority on Tuesday praised the agreement for the potential to accelerate the spread of high-tech 5G networks.
"The transaction will help secure US leadership in 5G, close the digital divide in rural America and strengthen competition in the broadband market," FCC Chairman Ajit Pai said in a statement.
The bureau's two dissenting Democrats were less optimistic. Commissioner Jessica Rosenworcel said the merger could mean the end of "a golden age in wireless," while Commissioner Geoffrey Starks said the agency's approval defied a staff analysis that found wireless prices could go up after the merger, especially for low-income city efforts.
But Starks said he found the conditions superfluous.
"I have little confidence that these obligations will protect competition and lead to the deployment of 5G services beyond what may have occurred in the absence of a merger," he said in a statement.
Despite the approval of the FCC and the Department of Justice, the agreement still faces roadblocks by a coalition of states that has sued to block the federal court merger. That case is expected to go to trial next month. T-Mobile and Sprint have said they will not attempt to end the merger unless the court decides in their favor.