Telephony system with automatic test call generator for remote port groups

• US 4,430,530 A
• Filed: 11/29/1982
• Issued: 02/07/1984
• Est. Priority Date: 08/24/1981
• Status: Expired due to Term

• Current Assignee: GEC Plessey Telecommunications Limited
• Original Assignee: Stromberg-Carlson Corp.
• Inventors: Kandell, Ronald J., Root, Bernard H., Merriam, Donald R., Woodruff, William W.
• Primary Examiner(s): SCHREYER, STAFFORD
• Application Number:
  US06/445,256
• Time in Patent Office: 435 Days
• Field of Search: 179/175.2 R, 179/175.2 C, 179/175.2 D, 179/175.3 R
• US Class Current: 379/29.01
• CPC Class Codes: H04M 3/244 for multiplex systems
• CPC Class Codes: H04M 3/323 for the arrangements providing the connection (test connection, test call, call simulation)

Abstract

A telephony network with a digital central office and one or more remotely located digital satellite units. Each digital satellite unit connects to a number of remote subscriber lines and monitors these lines to establish communications through interconnecting spans and a digital satellite interface at the digital central office. The digital satellite interface also connects to port group highways in the digital central switch, to call processors in the digital central switch, and to a maintenance processor in the digital central switch. An automatic test circuit communicates with the interface, and each remote digital satellite unit contains complementary testing circuitry. A test call is made to test the system by activating a test access relay at the remote digital satellite unit and producing a call to the automatic test circuit. The automatic test circuit then generates a tone that is carried as voice data to the remote digital satellite unit test circuit. If this tone is received, the test circuit at the digital satellite unit sends a tone followed by dial pulses. If the automatic test circuit receives the tone and dial pulses within specifications, the automatic testing has passed and no further action occurs. If it fails, a message is sent back to the digital satellite interface, so various levels of diagnostics utilizing the automatic test call circuit can be performed to isolate the cause of the failure.

Claims

1. A method for testing circuitry in a telephony network that comprises a digital central office with call processing means that transfer voice data and supervisory data, remote port units connected to remote subscriber lines, a communications link between the remote port units and the digital central office, interface means for interfacing the communications link, an automatic test call means for communicating through the digital central office means and a remote test call means in each remote port unit, said method comprising the steps of:

A. establishing a communications path between a remote test call means and the automatic test call means,

B. generating, in the automatic test call means, a first tone for transfer through the interface means as voice data to the remote test call means in response to the establishment of communicatins,

C. generating, in the remote test call means, a second tone for transfer through the interface means as voice data to the automatic test call means in response to the receipt of the first tone from the automatic test call means,

D. generating, in the remote test call means, signals corresponding to dial pulses for transfer as supervisory data through the interface means to the automatic test call means in response to the completion of the second tone, and

E. testing, in the automatic test call means, the second tone and dial pulse signals, and

F. generating, in the automatic test call means, an indication of success or failure of the test in response to said testing.

2. A telephony network comprising:

A. digital central office means with call processing means that transfer voice date and supervisory data,

B. remote port means connected to remote subscriber lines at a location that is remote from said digital central office means,

C. communications link means between said remote port means and said digital central office means,

D. interface means connected to said communications link means and said call processing means,

E. automatic test call means for communication through the interface means to said communications link means, said automatic test call means including;

(i) means for ascertaining the establishment of communications between said remote port means and the automatic test call means,

(ii) tone generating means for generating, in response to said establishment of communications, a first tone for transfer through the interface means as voice data,

(iii) testing means responsive to incoming signals from said interface means for testing second tone signals and dial pulse signals, and

(iv) means connected to said testing means for indicating the success of the testing, and

F. remote test call means in each said remote port means, said remote test call means including;

(i) tone generating means responsive to the receipt of the first tone from said automatic test call means for generating a second tone for transfer through said interface means to said automatic test call means, and

(ii) dial pulse generating means responsive to the completion of the second tone, for generating signals corresponding to dial pulses for transfer through said interface means to the automatic test call means.

3. Remote test call means as defined in claim 2 wherein said remote port means includes means for transmitting signals constituting voice data and supervisory data to, and for receiving signals constituting voice data and supervisory data from, the digital central office means over the communications link means, said remote test call means further comprising:

(a) bistable means connected to said remote port means and responsive to said supervisory data signals for generating a signal for initiating operations in said remote test call means; and

(b) state means for generating signals that sequentially identify a plurality of states, said state means including a counter connected to receive a plurality of signals from said remote test call means for causing said counter to advance in response to the successful completion of operations for each state identified by said counter.

4. Remote test call means as defined in claim 3 including means for generating timing signals and means for connection to at least one subscriber'"'"'s line circuit at the remote port means, the supervisory data signals including signals that identify the line circuit corresponding to the line under test, and further in which one of said states is a receive tone test state, said remote test call means including a receive tone test circuit including:

(a) a relay responsive to said bistable means for completing a circuit through the identified line circuit to enable the line circuit to receive the first tone signals;

(b) frequency test means connected to said state means and said line circuit for receiving the first tone signals and for generating a signal if the frequency of the received tone signal corresponds to an expected frequency; and

(c) means connected to said state means and said frequency test means for generating a signal a selected period of time after the beginning of the receive tone test state if the frequency test means is then generating a signal, thereby enabling the state means to advance to the next state.

5. Remote test call means as defined in claim 4 further comprising means connected to said state means, said frequency test means and said timing means for generating a test fail signal if said frequency test means is not generating a signal a selected time after the beginning of the receive tone test state.

6. Remote test call means as defined in claim 4 wherein one of said states is a tone generating state, said state means generating a signal identifying the beginning of said tone generating state, said tone generating means including a circuit for generating a tone signal and relay circuit means energized in response to the tone generating state signal for coupling the tone signal to the selected line circuit, said remote test call means further including:

A. timing means connected to said state means for generating a timing signal a selected time after the beginning of said tone generating state and

B. generating means connected to said timing means and to said state means and responsive to the timing signal and energization of said relay circuit means for generating a signal that enables said state means to advance to the next state a selected time after the beginning of said tone generating state.

7. Remote test call means as defined in claim 4 wherein one of said states is a dial pulse transmitting state, said state means generating a dial pulse test signal to initiate the dial pulse transmitting state, said remote test call means dial pulse generating means including means responsive to the dial pulse test signal to transmit dial pulses through said line circuit comprising:

A. dial pulse timing means connected to said timing circuit and said state means for generating a dial pulse relay enabling signal for a selected period of time after the initiation of the dial pulse transmitting state, and

B. a relay connected to said line circuit and energized in response to the dial pulse relay enabling signal for generating the dial pulse signal in response to the dial pulse timing signal.

8. Remote test call means as defined in claim 7 wherein said dial pulse timing means comprises:

A. means responsive to the dial pulse test signal for generating a dial pulse enabling signal, and

B. means responsive to said dial pulse enabling signal generating means and to said timing means for generating a dial pulse timing signal, and

C. means responsive to the coincidence of said dial pulse enabling signal and said dial pulse timing signal for generating said dial pulse relay enabling signal;

said dial pulse timing signal generating means being further connected to said state means to advance said state means at the end of each dial pulse timing signal.

9. Automatic test call means as defined in claim 2 wherein said digital central office means includes local port means that connect to local subscriber lines, said automatic test call means being connected to one of said local port means for transmitting voice data and supervisory data to, and receiving voice data and supervisory data from, the central office means, said local port means also receiving supervisory signals as supervisory data and timing signals from said digital central office means, said automatic test call means communication establishment ascertaining means including bistable means responsive to said supervisory signals and timing signals from said port means for generating a signal for initiating operations in said automatic test call means, said automatic test call means further comprising state means comprising:

A. counter means for generating signals that sequentially identify a plurality of states;

B. decoder means connected to said counter means and responsive to the state signals from the counter means for generating signals that initiate operations in the automatic test call means associated with each state; and

C. means connected to said communications establishment ascertaining means, said tone generating means and said testing means for advancing the counter means in response to the establishment of communications with a remote subscriber line, the generation of said first tone for a selected period of time and to the successful receipt of the second tone signals and dial pulse signals.

10. Automatic test call means as defined in claim 9 wherein said advancing means comprises:

A. timing means connected to said local port means and said counter means for generating a clocking signal for said counter means;

B. means connected to said counter means for generating an enabling signal transmitted to said counter means to enable it to advance in response to the successful completion of an operation for each state identified by said counter means.

11. Automatic test call means as defined in claim 10 wherein one of said states is a tone generating state during which said tone generating means generates digital tone signals, said tone generating means comprising:

A. means for storing a plurality of digital words constituting digital tone signals; and

B. means connected to said storing means and responsive to timing signals from said local port means for selecting words stored in said storing means for transmission.

12. Automatic test call means as defined in claim 11 wherein:

A. said storing means comprises a read only memory including a plurality of addressable storage locations each of which stores digital words constituting tone signals; and

B. said selecting means constitutes counter means connected to receive timing signals from the local port means, for sequentially generating signals that are coupled to said read only memory as address signals.

13. Automatic test call means as defined in claim 10 wherein one of said states is a received tone testing state, said testing means constituting:

A. means connected to said local port means for receiving tone signals from said local port means;

B. means for generating tone signals;

C. means connected to said tone receiving means and said tone generating means for comparing the received tone signals and the generated tone signals and for generating a signal if the signals match.

14. Automatic test call means as defined in claim 13 wherein:

A. said tone signals received from said local port means are in serial digital form, said receiving means including serial to parallel conversion means for converting said serial signals to parallel form;

B. said tone signal generating means comprises;

(i) memory means for storing digital words representative of tone signals in a plurality of addressable storage locations; and

(ii) address generating means connected to said memory means for generating address signals that are coupled to said memory means for selecting the digital words stored in said memory means, said address generating means being further connected to said comparing means for receiving a signal from said comparing means that inhibits it from advancing when said received tone signals and said tone signals from said memory means are not identical.

15. Automatic test call means as defined in claim 13 wherein each tone signal includes a signal indicating the sign of the tone signal, and said testing means further comprises means for testing the frequency of the received tone signals, comprising:

A. means connected to said tone signal receiving means for generating a signal when the received tone signals change sign; and

B. means connected to said sign change detecting means for determining whether the frequency with which the received tone signal changes sign is identical to an expected frequency, comprising;

(i) sign signal counter means connected to said sign signal generating means incremented in response to the receipt of a signal from said sign signal generating means;

(ii) frequency comparing means connected to said sign signal counter means for generating an output signal when the output signal from said sign signal counter means equals a predetermined count; and

(iii) means connected to receive timing signals from the local port means and the output signal from said frequency comparing means for generating a signal indicating the successful completion of the received tone test if the output signal from said frequency comparing means is received a preselected interval after the beginning of the received tone test.

16. Automatic test call means as defined in claim 10 wherein one of said states is a dial pulse test state in which supervisory data signals representative of dial pulse signals are received and counted to determine if a preselected number of dial pulse signals are received in a predetermined period of time, said automatic test call means further comprising dial pulse test means comprising:

A. dial pulse counter means connected to said state means and said local port means for receiving the dial pulse signals from said local port means, said state means enabling said dial pulse counter means to count the number of dial pulse signals received after the automatic test call means enters the dial pulse test state;

B. dial pulse comparing means connected to said dial pulse counter means for generating an output signal if the number of dial pulse signals is within a preselected range; and

C. dial pulse timing means connected to said dial pulse comparing means, said state means and said local port means for generating a signal a selected interval after the beginning of the dial pulse test state if the dial pulse comparing means is then generating an output signal.

17. Remote test call means as defined in claim 2 wherein said remote port means includes means for transmitting signals constituting voice data and supervisory data to, and for receiving signals constituting voice data and supervisory data from, the digital central office means over the communications link means, said remote test call means further comprising:

(a) bistable means connected to said remote port means and responsive to said supervisory data signals for generating a signal for initiating operations in said remote test call means; and

(b) state means for generating signals that sequentially identify a plurality of states, said state means including a counter connected to receive a plurality of signals from said remote test call means for causing said counter to advance in response to the successful completion of operations for each state identified by said counter.

18. Remote test call means as defined in claim 17 including means for generating timing signals and means for connection to at least one subscriber'"'"'s line circuit at the remote port means, the supervisory data signals including signals that identify the line circuit corresponding to the line under test, and further in which one of said states is a receive tone test state, said remote test call means including a receive tone test circuit including:

(i) a relay responsive to said bistable means for completing a circuit through the identified line circuit to enable the line circuit to receive the first tone signals;

(ii) frequency test means connected to said state means and said line circuit for receiving the first tone signals and for generating a signal if the frequency of the received tone signal corresponds to an expected frequency;

(iii) means connected to said state means and said frequency test means for generating a signal a selected period of time after the beginning of the receive tone test state if the frequency test means is then generating a signal, thereby enabling the state means to advance to the next state.

19. Remote test call means as defined in claim 18 further comprising means connected to said state means, said frequency test means and said timing means for generating a test fail signal if said frequency test means is not generating a signal a selected time after the beginning of the receive tone test state.

20. Remote test call means as defined in claim 18 wherein one of said states is a tone generating state, said state means generating a signal identifying the beginning of said tone generating state, said tone generating means including a circuit for generating a tone signal and relay circuit means energized in response to the tone generating state signal for coupling the tone signal to the selected line circuit, said remote test call means further including:

A. timing means connected to said state means for generating a timing signal a selected time after the beginning of said tone generating state and

B. generating means connected to said timing means and to said state means and responsive to the timing signal and energization of said relay circuit means for generating a signal that enables said state means to advance to the next state a selected time after the beginning of said tone generating state.

21. Remote test call means as defined in claim 18 wherein one of said states is a dial pulse transmitting state, said state means generating a dial pulse test signal to initiate the dial pulse transmitting state, said remote test call means dial pulse generating means including means responsive to the dial pulse test signal to transmit dial pulses through said line circuit comprising:

A. dial pulse timing means connected to said timing circuit and said state means for generating a dial pulse relay enabling signal for a selected period of time after the initiation of the dial pulse transmitting state, and

B. a relay connected to said line circuit and energized in response to the dial pulse relay enabling signal for generating the dial pulse signal in response to the dial pulse timing signal.

22. Remote test call means as defined in claim 21 wherein said dial pulse timing means comprises:

A. means responsive to the dial pulse test signal for generating a dial pulse enabling signal, and

B. means responsive to said dial pulse enabling signal generating means and to said timing means for generating a dial pulse timing signal, and

C. means responsive to the coincidence of said dial pulse enabling signal and said dial pulse timing signal for generating said dial pulse relay enabling signal;

said dial pulse timing signal generating means being further connected to said state means to advance said state means at the end of each dial pulse timing signal.

23. Automatic test call means for facilitating the testing of a telephone network that includes digital central office means with call processing means that transfer voice data and supervisory data, remote port means connected to remote subscriber lines at a location that is remote from said digital central office means, communications link means between the remote port means and the digital central office means, and interface means connected to said communications link means, said automatic test call means being connected for communicating through the digital central office means to said communications link means and comprising:

A. means for ascertaining the establishment of communications between said remote port means and the automatic test call means,

B. tone generating means for generating, in response to said establishment of communications, a first tone for transfer through the interface means as voice data,

C. testing means responsive to incoming signals from said interface means for testing second tone signals and dial pulse signals, and

D. means connected to said testing means for indicating the success of the testing.

24. Automatic test call means as defined in claim 23 wherein said digital central office means includes local port means that connect to local subscriber lines, said automatic test call means being connected to one of said local port means for transmitting voice data and supervisory data to, and receiving voice data and supervisory data from, the central office means, said local port means also receiving supervisory signals as supervisory data and timing signals from said digital central office means, said automatic test call means communication establishment ascertaining means including bistable means responsive to said supervisory signals and timing signals from said local port means for generating a signal for initiating operations in said automatic test call means and state means comprising:

A. counter means for generating signals that sequentially identify a plurality of states;

B. decoder means connected to said counter means and responsive to the state signals from the counter means for generating signals that initiate operations in the automatic test call means associated with each state; and

C. means connected to said communications establishment ascertaining means, said tone generating means and said testing means for advancing the counter means in response to the establishment of communications with a remote subscriber line, the generation of said first tone for a predetermined period of time and to the successful receipt of the second tone signal and dial pulse signals.

25. Automatic test call means as defined in claim 24 wherein said advancing means comprises:

A. timing means connected to said local port means and said counter means for generating a clocking signal for said counter means;

B. means connected to said counter means for generating an enabling signal transmitted to said counter means to enable it to advance in response to the successful completion of an operation for each state identified by said counter means.

26. Automatic test call means as defined in claim 25 wherein one of said states is a tone generating state during which said tone generating means generates digital tone signals, said tone generating means comprising:

A. means for storing a plurality of digital words constituting tone signals; and

B. means connected to said storing means and responsive to timing signals from said local port means for selecting words stored in said storing means for transmission.

27. Automatic test call means as defined in claim 26 wherein:

A. said storing means comprises a read only memory including a plurality of addressable storage locations each of which stores digital words constituting tone signals; and

B. said selecting means constitutes counter means connected to receive timing signals from the local port means, for sequentially generating signals that are coupled to said read only memory as address signals.

28. Automatic test call means as defined in claim 25 wherein one of said states is a received tone testing state, said testing means constituting:

A. means connected to said local port means for receiving tone signals from said local port means;

B. means for generating tone signals;

C. means connected to said tone receiving means and said tone generating means for comparing the received tone signals and the generated tone signals and for generating a signal if the signals match.

29. Automatic test call means as defined in claim 28 wherein:

A. said tone signals received from said local port means are in serial digital form, said receiving means including serial to parallel conversion means for converting said serial signals to parallel form;

B. said tone signal generating means comprises;

(i) memory means for storing digital words representative of tone signals in a plurality of addressable storage locations; and

(ii) address generating means connected to said memory means for generating address signals that are coupled to said memory means for selecting the digital words stored in said memory means, said address generating means being further connected to said comparing means for receiving a signal from said comparing means that inhibits it from advancing when said received tone signals and said tone signals from said memory means are not identical.

30. Automatic test call means as defined in claim 28 wherein each tone signal includes a signal indicating the sign of the signal, and said testing means further comprises means for testing the frequency of the received tone signals, comprising:

A. means connected to said tone signal receiving means for generating a signal when the received tone signals change sign; and

B. means connected to said sign change detecting means for determining whether the frequency with which the received tone signal changes sign is identical to an expected frequency, comprising;

(i) sign signal counter means connected to said sign signal generating means incremented in response to the receipt of a signal from said sign signal generating means;

(ii) frequency comparing means connected to said sign signal counter means for generating an output signal when the output signal from said sign signal counter means equals a predetermined count; and

(iii) means connected to receive timing signals from the local port means and the output signal from said frequency comparing means for generating a signal indicating the successful completion of the received tone test if the output signal from said frequency comparing means is received a preselected interval after the beginning of the received tone test.

31. Automatic test call means as defined in claim 25 wherein one of said states is a dial pulse test state in which supervisory data signals representative of dial pulse signals are received and counted to determine if a preselected number of dial pulse signals are received in a predetermined period of time, said automatic test call means further comprising dial pulse test means comprising:

A. dial pulse counter means connected to said state means and said local port means for receiving the dial pulse signals from said local port means, said state means enabling said dial pulse counter means to count the number of dial pulse signals received after the automatic test call means enters the dial pulse test state;

B. dial pulse comparing means connected to said dial pulse counter means for generating an output signal if the number of dial pulse signals is within a preselected range; and

C. dial pulse timing means connected to said dial pulse comparing means, said state means and said local port means for generating a signal a selected interval after the beginning of the dial pulse test state if the dial pulse comparing means is then generating an output signal.

32. Remote test call means for facilitating the testing of a telephone network that includes digital central office means with call processing means that transfer voice data and supervisory data, remote port means connected to remote subscriber lines at a location that is remote from said digital central office means, communications link means between the remote port means and the digital central office means, and interface means connected to said communications link means, and automatic test call means including means for generating a first tone for transfer through the interface means and communications link means to the remote port means, said remote test call means being connected to the remote port means and the communications link means and comprising:

A. tone generating means responsive to the receipt of a first tone from the automatic test call means for generating a second tone for transfer through said interface means to the automatic test call means, and

B. dial pulse generating means responsive to the completion of the second tone, for generating signals corresponding to dial pulses for transfer through said interface means to the automatic test call means.