Patents by Inventor Leon Hall

Leon Hall has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Apparatus for converting a standard telephone to an unlisted number telephone
    Patent number: 4639552
    Abstract: The apparatus of this invention is a system which is attached to a standard telephone instrument at a receiving station. When a call comes from a transmitting station through a switching station, this call is received in this apparatus, which signals the transmitting station to send its private code. After validating this code, it serves to indicate information about the transmitting station. The receiving station then has the option to answer or not to answer.
    Type: Grant
    Filed: March 8, 1985
    Date of Patent: January 27, 1987
    Inventor: Leon Hall