US 4,794,632 AGranted

Telephone trunk line testing circuitry

AssigneeMinnesota Mining and Manufacturing Company

InventorsPeter G. Burton, James K. Kennedy

Life of this patent

Estimating the term…

Loading patent…

Abstract

Telephone trunk line testing circuitry for connection to a private branch exchange (PBX) and the telephone trunk lines for the PBX including a microcomputer unit (MCU), switching circuitry, a DTMF receiver, and a tone generator for connecting one of the trunk lines as a control trunk for the circuitry. Under the control of the MCU programmed to respond to DTMF various signal commands sent from a telephone at the far end of the control trunk the circuitry operates to selectively disconnect (isolating) one of the other trunks at a time from the PBX and connect it to the circuitry with the circuitry configured under control of the MCU for completing various test involving the trunk under test (TUT), control trunk, switching circuitry and the tone generator, including the supply of tone signals from the tone generator during some of the test configurations.

Telephone trunk line testing circuitry for connection to a private branch exchange (PBX) and the plurality of telephone trunk lines of the public telephone system provided for the PBX, the testing circuitry including:

a microcomputer unit (MCU);
first means connected to said MCU and having a receive input and a transmit output for transmission of signals under the control of said MCU between said receive input and said transmit output;
a dual tone multiple frequency (DTMF) receiver connected to said MCU and operably connected to receive any signals presented to said receive input;
a tone generator operatively controlled by said MCU and operatively connected to said transmit output;
a first pair of transmission paths;
a second pair of transmission paths;
a first switching means operatively controlled by said MCU programmed for selectively providing any one of the following connecting conditions:
(1) connecting said first pair of transmission paths to said receive input and said second pair of transmission paths to said transmit output;
(2) connecting said first pair of transmission paths to said transmit output and said second pair of transmission paths to said receive input;
and
(3) connecting said first pair of transmission paths to said second pair of transmission paths;
first switch means operably connected to said MCU for selecting a trunk line as a control trunk line;
and
second means operably controlled by said MCU, when said first switching means presents said connecting condition (1), for coupling the control trunk line selected by operation of said first switch means to said first pair of transmission paths following the completion of a call via the public telephone system between a DTMF type telephone and the control trunk line selected by operation of said first switch means, said control trunk when so connected serving to transmit any DTMF signals to said DTMF receiver that are generated by operation of the keyboard of the DTMF type telephone.

11 more elements

Abstract

Claims17