“With text-messaging rates doubling over the past three years, Sen. Herb Kohl has started asking questions. The Wisconsin Democrat and head of the Senate’s antitrust subcommittee sent a letter to the four major cellular companies on Tuesday with some interesting points.

In 2005, the industry charged about 10 cents per text. Now it’s 20 cents. All four carriers upped their rates at about the same time. The number of nationwide competitors slipped from six to four. And the remaining big-timers are gobbling up regional carriers.”

US Senator Herb Kohl’s press release includes the letter to the telecos.

“Today, US Senator Herb Kohl (D-WI), chairman of the Senate Antitrust Subcommittee, asked the presidents and chief executive officers of the four largest wireless telephone companies to justify sharply rising rates for its customers to send and receive text messages. In a letter, Senator Kohl requested an explanation from Verizon Wireless, AT&T, Sprint and T-Mobile, which collectively serve more than 90 percent of the nation’s cellular phone users. The text of Senator Kohl’s letter follows below.”