Sometimes clunky old technologies hang around much longer than the problems they originally solved. The 12-button alphanumeric telephone keypad is a prime example. The letters on each key–“ABC” on the 2 key, “DEF” on the 3 key, and so on–are a legacy of the 1920s, when phone numbers typically started with the first two letters of local telephone exchanges. Students of TV trivia, for example, may remember that the phone number at Lucy and Ricky Ricardo’s New York apartment was MUrray Hill 5-9975.

Ma Bell left the alphabet on phones even after the abandonment of exchange names in the late 1950s. The letters didn’t have much use until the advent of vanity dialing in the 1980s (e.g., 1-800-GET-RICH) and the explosion of mobile text messaging in the late 1990s. But now text messaging is at the core of the world’s wireless culture–and the 12-button keypad layout forces billions of mobile subscribers to “triple-type,” pressing keys up to three times to get the letters they want (and up to eight or nine times if their local writing system uses more letters than the Latin alphabet does).

While millions of teens have mastered triple typing on their 12-button phones, it’s an inefficient way to enter text, especially for fat-fingered adults. “If it were a new invention, people would think that it was a very poor idea,” says David Levy, an inventor and former ergonomic designer at Apple.

In fact, Levy thinks that people are so fed up with triple typing that they’re finally ready for a new keypad design, one that places each letter in alphabetical order, without adding a space-consuming QWERTY keyboard like those on RIM’s BlackBerry pager or Palm’s Treo cell phones. Levy’s idea, which he patented in 1993, is simply to place raised letter keys in the corners between the numeric keys. By a happy coincidence, an 18-button numeric keypad (counting navigation keys, special characters, and buttons for starting and ending calls) has 28 available corners; Levy’s design uses all of them except the bottom left and bottom right.

The new layout, called Fastap, is the first major overhaul of the traditional phone keypad since it debuted on touch-tone phones in the 1960s. Levy founded Digit Wireless, based in Lexington, MA, in 2005 to license the idea to phone manufacturers. So far, two mobile operators–Alltel in the United States, and Telus in Canada–have introduced Fastap phones, both made in South Korea by electronics giant LG. (Telus offers the LG 490, and Alltel offers the nearly identical AX490.)

Levy says that the phones are being purchased by mainstream mobile-phone users, not by the geeks and mobile executives who are already addicted to messaging on their BlackBerrys and Treos. And once they buy a Fastap phone, these customers send twice as many text messages as they did on their previous phones, according to usage data collected by Telus over a period of nine months. Most mobile operators charge by the message, so that’s the kind of number they like to hear. “From the consumer perspective, our technology is all about making the phone more usable and fun,” says Levy. “But for the carrier, it’s all about money. Fastap satisfies both needs at the same time.”

In contrast to expensive Treos and BlackBerrys, phones with the extra keys for the Fastap system are only slightly more expensive to manufacture than traditional mobile phones are, according to Levy. Alltel and Telus are offering them to customers at subsidized prices similar to those for their other phones–$9.99, with a long-term contract, in Alltel’s case.

Superimposing alphabetic keys on a numeric keypad may sound like a simple idea, but Levy says that some software trickery was required to make it work in practice. The problem is that the Fastap design fits more than twice as many keys into the same area as a traditional keypad. Raising the letter keys gives users tactile feedback that helps them distinguish the letter keys from the number keys. But occasionally, users who intend to press number keys may accidentally press letter keys first, or roll their fingers from number keys onto letter keys.

When adjacent letter and number keys are pressed in quick sequence, algorithms programmed into the Fastap phones always give priority to the lower number keys. Similar algorithms deal with cases in which the users’ fingers roll from a number key onto a letter key, or in which two diagonal letter keys are pressed together. Because the software automatically corrects such fumbles, the “touch area” available around each key is effectively the same as that of keys on a laptop computer.

On average, experienced Fastap users write text messages three times faster than triple typers do, Levy claims. He says that users adapt quickly to the alphabetical order of the Fastap keyboard, even if they’re accustomed to the QWERTY keyboards of computers and BlackBerry-type devices.

Levy says that Digit Wireless is in negotiations with more mobile-phone manufacturers and carriers, and he expects that Fastap phones will be available soon in Mexico, South America, Europe, and Asia. The company is also exploring alternate bi-level keypad layouts that would accommodate larger alphabets, such as Cyrillic (with 32 letters), Thai (49), and Hindi (60). In those cases, users might have to do some double typing to select the intended letter, Levy says. “But if you go from an average of eight taps down to two, there is still a huge benefit.”