Alphanumeric keyboard with telephone dialing capability

Abstract

An alphanumeric keyboard connects to a telephone line and is operable in two operating modes. The keyboard is in a first operating mode when the telephone is in an 'off-hook' condition and no connection on the telephone line has been established. In the first operating mode, the keyboard generates telephone number dialing signals on the telephone line as corresponding alphanumeric keys of the keyboard are pressed. Thus for example as a user enters the letters D-O-G by pressing the corresponding single-letter keys of the keyboard, the signaling tones for the digits 3, 6 and 4 are generated on the telephone line. In an enhanced version, the keyboard assigns distinct signal tones, such as an expanded dual tone multi-frequency (DTMF) set, to each alphanumeric character, thereby significantly increasing the quantity of potential telephone numbers. The keyboard operates in a second operating mode when the telephone is in an off-hook condition and a connection on the telephone line has been established. In this mode, the keyboard generates alphanumeric character code signals such as ASCII code signals on the telephone line as corresponding keys of the keyboard are pressed. This feature enables cooperating equipment on the other end of the line to receive text messages and other data from the keyboard after a connection has been established. An enhanced version of the keyboard has a processor, memory and a display to permit a variety of additional features to be realized, such as electronic mail messaging.