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Telephone keypad matrix

  • US 5,117,455 A
  • Filed: 03/28/1990
  • Issued: 05/26/1992
  • Est. Priority Date: 03/28/1990
  • Status: Expired due to Fees
First Claim
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1. A method for the entry of numerical characters and alphabetical characters into a telephone system, the telephone system having a keypad, a speaker, a microphone, a receiving station, and memory, the method comprising:

  • prearranging the characters of the alphabet on the keypad so that only one character is placed between any two adjacent keys of the keypad; and

    defining at least one keypair for each alphabetical character by selecting at least one key adjacent to each character, the keypairs generating dual tone multifrequency signals corresponding to character codes stored within the memory of the telephone system, each keypair operated by two sequential keystrokes of the at least one adjacent key, in either sequence.

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