Patents by Inventor John R. Whitbread

John R. Whitbread 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).

  • Telephone call denial system
    Patent number: 4355208
    Abstract: A call denial apparatus for identifying a telephone subscriber's line out of a group, whereby access to a trunk is denied in the event the subscriber dials one or a group of predetermined digits. A subscriber not to be denied access to the trunk is identified by applying a tracer signal to the seized trunk and the tracer signal on one of the group of subscribers' lines is detected. Accordingly specially modified telephone sets and lines are not required.
    Type: Grant
    Filed: November 5, 1980
    Date of Patent: October 19, 1982
    Assignee: Mitel Corporation
    Inventors: John A. Cribb, John R. Whitbread, Graham Neathway, Robert A. Durance