The FCC has received more than 10,000 comments about the proposed merger, with many mobile customers submitting one-page form letters from media reform group Free Press in opposition to the deal.

"If you even bother to read this, I have a reminder for you; the reason you got into politics in the first place -- to serve the people," one person wrote. "Corporations aren't people. Go get your backbone and integrity out of the closet, dust 'em off, and wear them proudly. Try to remember who you serve."

Several groups have filed comments in support of the deal before the Tuesday deadline for petitions to deny the acquisition.

"The result of the proposed merger of T-Mobile and AT&T is expected to be near-universal access to broadband Internet service," wrote J.R. Jones, president and CEO of the Mississippi Black Chamber of Commerce. "We expect the minority businesses we represent to be some of the primary beneficiaries of this expanded network commitment."

AT&T has said the deal will allow it to expand mobile broadband service to 97 percent of the U.S. population.