The U.S. Justice Department has begun looking at big telecom companies to try to determine if they have abused their market power, the Wall Street Journal reported in its online edition on Monday.
The journal, which cited people familiar with the matter, said that the Antitrust Division's review was in its very early stages and was not official.
Lawmakers have recently raised questions about whether large wireless carriers were hurting smaller rivals by entering exclusive agreements with the makers of popular phones.
They have also raised questions about the pricing of text messages.
(Reporting by Diane Bartz; Editing by Tim Dobbyn)