Telephone line status circuit
AssigneeMitel Corporation
InventorsJohn A. Barsellotti, Douglas C. Oddy
Life of this patent
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Abstract
A circuit for detecting a first plurality of status signals on a multiplicity of telephone lines and generating a second lesser plurality of control signals, less than the first plurality, in response thereto. Predetermined ones of the control signals are transmitted via a multiplexing circuit to a comparator circuit. A digital-to-analog converter generates analog threshold voltages for application to the comparator circuit in response to receiving command signals from a microprocessor. The comparator circuit generates a third lesser plurality of output signals, less than the second plurality, indicative of the status of a multiplicity of remote trunk circuits connected to the telephone lines. The circuit is inexpensive and occupies little circuit board area.
Claims25
A line status circuit for connection to a PABX and one or more telephone lines carrying a first plurality of status signals indicative of the status of one or more remote telephone circuits, comprised of:
- (a) a control circuit for generating command signals,
- (b) means for receiving said status signals carried by said one or more telephone lines, and generating control signals in response thereto,
- (c) means for receiving one or more first command signals from the control circuit and generating one or more threshold signals in response thereto, and
- (d) means for receiving one or more second command signals from said control circuit, and in response comparing predetermined ones of said control signals with said one or more threshold signals, and generating a plurality of output signals less than said first plurality of status signals, whereby said output signals provide an indication to said PABX of the status of said remote telephone circuits.
A line status circuit for connection to a PABX and one or more telephone lines carrying a first plurality of status signals indicative of the status of one or more remote telephone circuits, comprised of:
- (a) a control circuit for generating one or more command signals,
- (b) means for receiving said first plurality of status signals carried by said telephone lines, and generating a second plurality of control signals, less than said first plurality in response thereto,
- (c) means for generating a sequence of threshold signals in response to receiving a sequence of first command signals from said control circuit, and
- (d) means for receiving a sequence of second command signals from said control circuit, and in response comparing successive ones of said control signals with successive ones of said threshold signals, and generating a sequence of output signals, whereby said output signals provide an indication to said PABX of the status of said remote telephone circuits.
A line status circuit for connection to a PABX and a plurality of telephone lines carrying status signals generated by a plurality of remote trunk circuits, comprising:
- (a) controller means for generating digital command signals,
- (b) one or more local trunk circuits connected to said telephone lines for receiving status signals carried by said telephone lines and generating control signals in response thereto,
- (c) multiplexer means having signal inputs thereof connected to said local trunk circuits and control inputs thereof connected to said controller means, for transmitting a predetermined sequence of said control signals in response to receiving a predetermined sequence of command signals from said controller means,
- (d) means for receiving a further sequence of command signals from said controller means, and generating a sequence of threshold signals in response thereto, and
- (e) comparator means connected to said multiplexer means and said means for generating threshold signals, for comparing successive ones of said transmitted control signals with successive ones of said of threshold signals and generating a sequence of output signals for transmission to said PABX in response thereto, whereby said sequence of output signals provides an indication to said PABX of the status of successive ones of said remote trunk circuits.
Dependencies are inferred from the claim text.