| 摘要 |
A software driven, timing dependant method for entering alphanumerical characters using a conventional push button telephone system having automatic response functions is based upon the position (first, second or third) of each alphabetic letter upon each key of the standardized telephone keypad matrix. DTMF signals are generated following the pressing of a key to identify the key pressed and thereby generate a sequential message menu for that particular key. The key is pressed a predetermined number of times (once, twice, or three times) to select the desired letter, and the letter signals are transmitted to conventional voice tone recognition apparatus and storage facilities. The first, second and third messages on each key each consist of a silence interval segment of known length followed by, respectively, a first, second and third letter interval segment of known length. Each message may be interrupted by pressing the same, or another, key again prior to expiration of a predetermined portion of the combined message segments. Interruption of a message causes the system to rotate to the next available message. A digit is entered by pressing the desired digital key followed by pressing of "pound" sign key, or by sequentially pressing the desired digital key four times.
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