U.S. wireless carriers Verizon Communications and AT&T took issue with assertions that they colluded in setting prices for text messages, saying that prices for most customers had fallen and the market was competitive. Sen. Herb Kohl, chair of the Senate Judiciary Committee's antitrust subcommittee, said he was concerned that the four largest cell phone companies doubled their text message rates from 10 cents in 2006 to 20 cents in 2008.