Under the agreement, Verizon Wireless would acquire a swath of spectrum from Comcast, Time Warner Cable and Bright House Networks (as well as Cox, in a separate transaction) and the firms would enter into joint marketing and operating agreements through which they would promote and sell each other's services.

But for critics who warn against greater consolidation in the telecommunications sector, the deal would further an alarming trend and erode competition, likely driving up prices.

"We should be very careful about approving deals like this which turns competitors into collaborators," Rep. Jerrold Nadler (D-N.Y.) told reporters on a conference call. "This should raise serious red flags."

In July, Nadler was one of 32 members of Congress who signed a letter to the heads of the Justice Department and Federal Communications Commission urging a close review of the transaction and suggesting that the deal violates provisions of the 1996 Telecommunications Act concerning marketplace diversity.

"We want firms to compete, not capitulate or collaborate," Nadler said.