Anyone who has ever placed a telephone call is familiar with the fact that the 2-9 keys of a standard phone dial are each labeled with three letters of the alphabet (the letters Q and Z do not appear). However, the overloading of three letters on a single key creates a potential ambiguity as to which character was intended. Resolving this overloading is necessary for unambiguous text entry.

Existing systems use pairs of keypresses to spell out single letters, such as using the first key to specify a triple of letters and the second to select the correct one from the triple. These systems are extremely cumbersome and frustrating to use, whereas significantly increased typing speeds can be obtained with single keypresses. Applications of our technology include:

E-mail without a terminal
The phone keypad and either an LCD display or text-to-speech synthesizer facilitate arbitrary interaction with a computer, enabling the user to read and write E-mail from a conventional or cellular phone without additional hardware.

Communication with the hearing-impaired
With a computer-enhanced telephone, a hearing-impaired user could make and receive calls to a conventional telephone without the intervention of an outside operator. The hearing-impaired user would communicate via a computer screen, while the other user would type on the phone keypad and hear results dictated by a text-to-speech synthesizer.

Enhanced voice-response systems
Conventional voice-response systems record certain user-interactions, which must be transcribed before they can be acted upon. Using our techniques, a user's name and address could be entered and reconstructed with sufficient fidelity that requested literature could be mailed immediately, without human intervention.