KEYPAC - A Telephone Aid for the Deaf

This paper presents a telecommunications system, KEYPAC (Key Phone Alphanumeric Communication), that enables a user to communicate over the telephone without the use of speech. The design of this system was motivated by the need for a low cost, yet simple and useful means of telephone communication in the deaf community. The KEYPAC system provides a flexible means for speechless telephone communication by utilizing an ordinary pushbutton telephone as a transmitting device. Alphanumeric messages are sent by pressing sequences of keys according to a simple coding scheme of two keys per letter and one key per number (0-9). Message reception is accomplished with the use of a small, hand-held receiver that is attached to the telephone. The receiver decodes sequences of D.T.M.F. (Dual Tone Multi Frequency) audio tones and displays the resulting messages on a visual display or hard copy printer.