Patents by Inventor Robert A. Durance

Robert A. Durance 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
  • Junctor checking system
    Patent number: 4167656
    Abstract: A junctor checking system for an electronic PABX which checks the potential of the junctor under control of a microprocessor. A voltage level sensing circuit is connected to the junctor to be checked; a resistor connects the input of the voltage level sensing circuit to a voltage source. In the event the impedance of the junctor to ground is not as expected with respect to at least one threshold, the junctor is considered faulty and a different idle junctor is selected.
    Type: Grant
    Filed: August 14, 1978
    Date of Patent: September 11, 1979
    Assignee: Mitel Corporation
    Inventors: Robert A. Durance, John A. Cribb