The first was AT&T Wireless, which announced the service late January. Cingular Wireless soon followed suit.
Text messages sent over wireless networks to cell phones are similar to e-mail, but are generally limited to 150 characters and can't support attachments. In general, a wireless subscriber can receive a text message for free, but it costs between 4 cents and 10 cents to send a message.
Text messaging is just one of many ways in which wireless carriersto find new sources of revenue, primarily to offset the cost of new cell phone networks--projects that have run into the billions of dollars.
Still more carriers are expected to follow AT&T Wireless' lead.
"Their traffic took off, and now everybody wants it," said Scott Ellison, program director of wireless and mobile communications for analyst firm IDC.
Cingular plans to launch the service in March for subscribers across the nation, said Kris Rinne, vice president of product development and technology. Some of the network is already up and running, she added.
Cingular said it has experienced a 450 percent increase in message traffic since January. AT&T spokesman Ritch Blasi said the carrier has seen message traffic doubleit let subscribers send messages to most other U.S. carriers.
AT&T Wireless hired InphoMatch, which makes equipment to help carriers offer wireless messaging services. InphoMatch President Colin Montgomery said VoiceStream's network has already been outfitted with the same type of equipment as of Jan. 21.
He is unsure why the company hasn't launched any service yet, perhaps waiting to announce the availability at next month's Cellular Telecommunications and Internet Association conference. A VoiceStream Wireless representative did not return repeated telephone calls for comment.
"VoiceStream launched in late January, and it's common knowledge," Montgomery said. "But they haven't announced it yet, officially. What can I tell you?"
The United States still lags behind Europe in the popularity of text messaging, according to the latest statistics. Last year, there were about 176 million e-mails sent between cell phones in the United States, according to Ellison. Next year, he believes that number will increase to 1.5 billion wireless e-mails sent. By comparison, there are an estimated 30 billion messages exchanged every month in Europe. Carriers wouldn't confirm these estimates.
"That whole thing with SMS (Short Messaging Service) in Europe didn't happen overnight," said Keith Waryas, a wireless analyst with IDC. "There are still a lot of issues to get around, like typing messages on that tiny keyboard."