WASHINGTON – Lawmakers expressed concern Tuesday that a lack of competition in the wireless industry has led to unfairly high prices for consumers beholden to a handful of providers.

From 2006 to 2008, four dominant wireless carriers twice raised the price for text messages by the same amount within months of one another, Sen. Herb Kohl, D-Wis., said during a Senate Judiciary subcommittee hearing.

"These lockstep price increases occurred despite the fact that the cost to the phone companies to carry text messages is minimal – estimated to be less than a penny per message – and has not increased," Kohl said.

Kohl said the price of a single text message increased 100 percent, from 10 cents to 20 cents, from 2006 to 2008. He said that true competition among the four major companies – Dallas-based AT&T Inc., Verizon Communications Inc., Sprint Nextel Corp. and T-Mobile USA Inc. – should have put downward pressure on prices over that period.

Executives from wireless companies said the price of a single text message isn't a good indicator of competition because avid texters purchase plans with hundreds of messages per month, and revenue from "pay-per-use" text messages are a small factor on their balance sheets.

They said companies compete on other offerings – such as devices and plans.

"Against this backdrop of white-hot competition, we can put to rest an underlying implication of the subcommittee's inquiry into this matter – that the national wireless providers may have conspired to fix prices for text messaging," said Wayne Watts, senior executive vice president and general counsel of AT&T.

Service has also improved while the overall prices of cellphones have continuously fallen, "which are the markings of a competitive – not collusional – market," said Randal Milch, executive vice president and general counsel of Verizon.

Kohl said the wireless landscape prevents start-up companies from gaining a foothold, concentrating the power of a few companies. He urged the Federal Communications Commission to remove barriers to competition that keep smaller wireless companies out of the marketplace.

Joel Kelsey, a policy analyst for Consumers Union, a nonprofit advocacy group, said the problem isn't limited to text messaging; he said the companies also have a stranglehold on the industry because of exclusive contracts with vendors.

But Watts – representing the company that has exclusive rights over Apple's wildly popular iPhone – said the current system promotes innovation and competition and helps keep prices down as wireless providers are often forced to subsidize the cost of the devices they sell.

"Every phone manufacturer is spending enormous amounts of money to create the 'iPhone killer,' " Watts said.