THE TESTING OF TELEPHONE LINES

Abstract: A telephone line testing device for use with a PABX having a plurality of input lines. The testing device includes test circuitry, a first connecting means for connection to a telephone line of a telephone system, a second connecting means for connection to a desired input line of the PABX, a first switch means for connecting either the PABX input line or the test circuitry to the telephone line. The test circuitry includes a test signal generating means for generating a test signal, a ringing signal detection means for detecting the presence of a ringing signal on the telephone line, and a second switch means which is responsive to the ringing signal detection means for automatically supplying a test signal generated by the test signal generating means to the telephone system when the test circuitry is connected to the telephone line by the first switch means and a ringing signal is detected.

Description: THE TESTING OF TELEPHONE LINES THIS INVENTION relates to a telephone line testing device and to a method of testing a telephone line. More particularly, the invention relates to a telephone line testing device and method for use with a PABX. According to the invention there is provided a telephone line testing device for use with a PABX having a plurality of input lines, which includes test circuitry; a first connecting means for connection to a telephone line of a telephone system; a second connecting means for connection to a desired input line of the PABX; a first switch means for connecting either the PABX input line or the test circuitry to the telephone line; with the test circuitry having a test signal generating means for generating a test signal; a ringing signal detection means for detecting the presence of a ringing signal on the telephone line; and a second switch means which is responsive to the ringing signal detection means for automatically supplying a test signal generated by the test signal generating means to the telephone system when the test circuitry is connected to the telephone line by the first switch means and a ringing signal is detected . Further according to the invention there is provided a method of testing a telephone line connected to a PABX which includes disconnecting the PABX from the telephone line and connecting test circuitry to the telephone line; detecting the presence of a ringing signal on the telephone line by means of the test circuitry; and automatically supplying a test signal generated by a test signal generating means included in the test circuitry to the telephone line. It will be appreciated by those skilled in the art that the test signal generating means may be connected directly to the first switch means and may then be energised by the second switch means when a ringing signal is detected, or it may be connected to the first switch means via the second switch means. If the test signal generating means is connected directly to the first switch means it may have a sufficiently high impedance so that the telephone line is not closed when the first switch means is operated . The first connecting means may include a plurality of first terminals to which a corresponding number of telephone lines may be connected. The second connecting means may also include a plurality of second terminals to which a corresponding number of PABX input lines may be connected, there being the same number of second terminals as there are first terminals, and with designated first and second terminals being associated with one another. The first switch means may include a plurality of mechanically operable switches, each switch having a first contact connected to an associated first terminal, a second contact connected to the second terminal associated with said first terminal, a third contact connected to the test circuitry, and a contactor for connecting the first contact to either the second or third contact. The ringing signal detection means may be connected to all the third contacts of the first switch means. The test signal generating means may be connected to all the third contacts of the first switch means via the second switch means. The telephone testing device may have a lightning protection means. The telephone line to be tested may be accessed via the PABX, using another telephone line. By means of the invention a PABX telephone operator may, if he believes that one of the telephone lines is faulty, easily and quickly identify which telephone line it is. The invention is now described, by way of an example, with reference to the accompanying drawings, in which:- Figure 1 shows a schematic circuit diagram of a telephone line testing device in accordance with the invention connected to a PABX and a telephone line; Figure 2 shows schematically how the telephone testing device is connected to a plurality of telephone lines; and Figure 3 shows a schematic circuit diagram of a second embodiment of test circuitry. Referring now to Figure 1 , a telephone line testing device in accordance with the invention is generally indicated by reference numeral 10. The telephone line testing device 1 0 includes test circuitry 1 3, a first connecting means 14 for connection to a telephone line 12 of a telephone system, a second connecting means 1 5 for connection to an input line 16 of a PABX 90 1 7, a third connecting means 18 for connection to the test circuitry 13, and a first switch 1 9 for connecting either the PABX line 16 or the test circuitry 1 3 to the telephone line 1 2. The connecting means 14, 1 5 and 18 are in the form of sets of terminals 20.1 and 20.2, 21 .1 and 21 .2, and 22.1 and 22.2, respectively. The first switch 19 has contacts 25.1 and 25.2, 27.1 95 and 27.2, and 29.1 and 29.2 and contactors 31 .1 and 31 .2, such that the first switch 19 is a double pole type switch. The contactors 31 .1 and 31 .2 are manually operated and connect either the contacts 25.1 and 25.2 to the contacts 27.1 and 27.2 respectively or to the contacts 29.1 and 29.2 respectively. As indicated, the terminals 20.1 and 20.2 are connected to 00 the contacts 25.1 and 25.2 respectively; the terminals 21 .1 and 21 .2 are connected to the contacts 27.1 and 27.2 respectively; and the terminals 22.1 and 22.2 are connected to the contacts 29.1 and 29.2 respectively. The test circuitry 13 has a test signal generator 26 provided with an 05 activation switch 38; a ringing signal detector 28 for detecting the presence of a ringing signal on the telephone line 1 2; and a second switch 30 which is responsive to the ringing signal detector 28 for automatically connecting the test circuitry 13 to the telephone system when the test circuitry 13 is connected to the telephone line 12 by the switch 1 9 and a ringing signal is 10 detected. The test signal generator 26 generates a suitable audible signal. The test circuitry 13 includes a DC blocking capacitor 32, a rectifying bridge 34 and a storage capacitor 36. The second switch 30 is in the form of a relay, having a coil 30.1 and normally open contactors 30.2 and 30.3. The contactor 30.2 bypasses the blocking capacitor 32 when a ringing signal is detected. The contactor 30.3 connects the test signal generator 26 to the telephone line 1 2. The rectifying bridge 34 has two LED's 34.1 and 34.2. As seen in Figure 1 , the telephone line 12 has two cores 33.1 and 33.2. Similarly, the PABX line 16 has two cores 35.1 and 35.2. The cores 33.1 and 33.2 are connected to the terminals 20.1 and 20.2 respectively. The cores 35.1 and 35.2 are connected to the terminals 21 .1 and 21 .2 respectively. The test circuitry 13 is connected to terminals 22.1 and 22.2 by a two core wire having cores 23.1 and 23.2. The rectifier bridge 34 is connected to terminals 22.1 and 22.2 via the blocking capacitor 32. The test signal generator 26 is also connected to terminals 22.1 and 22.2 via the second switch 30. The method for determining whether there is a fault in the telephone line 12 upstream from the PABX 1 7 includes operating the first switch 1 9 to disconnect the telephone line 1 2 from the PABX 17 and connect the telephone line 1 2 with the test circuitry 13. The telephone line 12 is dialled by an operator using the PABX 1 7 or some other telephone instrument. If the line 1 2 is functional, the alternating current caused by the ringing tone is converted to a direct current by the rectifier bridge 34 causing the relay 30 to close the telephone line 1 2 and connect the operator's telephone to the test signal generator 26 which provides an audible signal which is heard by the operator. In addition, when relay 30 closes, the contactor 30.2 bypasses the blocking capacitor 32 causing the LED 34.1 or 34.2 to indicate a direct current. If the telephone line 1 2 is not functional the test signal is not heard and/or the LED's 34.1 and 34.2 are not energised. If the test signal is heard and/ or LED 34.1 or 34.2 emits light then the fault originates at the PABX 1 7 and if no test signal is heard or no light emitted by LED 34.1 or 34.2 then the fault originates from the telephone line 1 2. Referring now to Figure 2, a multiple switch system in accordance with the invention is generally indicated by the reference numeral 40. The multiple switch system comprises a number of switches 1 9.1 , 1 9.2 to 1 9.N which are connected to a corresponding number of telephone lines 1 2.1 , 1 2.2 and 1 2.N and PABX lines 1 6.1 , 1 6.2 and 1 6.N. Each switch 1 9.1 , 1 9.2 to 1 9.N is as shown in Figure 1 , with each telephone line 1 2.1 , 1 2.2 to 1 2.N having two cores connected to the terminals 20.1 and 20.2 of its associated switch and each PABX line 1 6.1 , 1 6.2 to 1 6.N having two cores connected to the terminals 21 .1 and 21 .2 of its associated switch. The test circuit 1 3 is connected to the terminals 22.1 and 22.2 of all the switches 1 9. Any one of the telephone lines 1 2.1 , 1 2.2 to 1 2.N can be connected to the test circuitry 13 to enable an operator to test that particular line. Referring now to Figure 3, a second embodiment of test circuitry 13.1 is shown. This embodiment 13.1 has cores 23.1 and 23.2 which are connected to the terminals 22.1 and 22.2. It further has an IC test signal generator 26.1 which is connected to the cores 23.1 and 23.2 by means of a full wave rectifier 34, a transformer 54, an SCR switch 56 and a signal capacitor 58. It also has a ringing signal detector 28.1 also connected to the cores 23.1 and 23.2. This ringing signal detector comprises a half wave rectifier 60, a charging capacitor 62 and an opto coupler 64 which is connected to the gate of the SCR 56. In use, when the test circuitry 13.1 is connected to an operative telephone line, and an AC ringing signal is received, it is rectified by the rectifier 60, the capacitor 62 charges and the opto coupler 64 triggers the SCR 56. When the SCR 56 is switched on it supplies power to the IC 26.1 and the audible test signal is then supplied to the telephone line. When the line is disconnected, the test circuitry is deenergised and reset.

Claims: CLAIMS 1 . A telephone line testing device for use with a PABX having a plurality of input lines, which includes test circuitry; a first connecting means for connection to a telephone line of a telephone system; a second connecting means for connection to a desired input line of the PABX; a first switch means for connecting either the PABX input line or the test circuitry to the telephone line; with the test circuitry having a test signal generating means for generating a test signal; a ringing signal detection means for detecting the presence of a ringing signal on the telephone line; and a second switch means which is responsive to the ringing signal detection means for automatically supplying a test signal generated by the test signal generating means to the telephone system when the test circuitry is connected to the telephone line by the first switch means and a ringing signal is detected. 2. The telephone line testing device as claimed in Claim 1 , in which the first connecting means includes a plurality of first terminals to which a 200 corresponding number of telephone lines may be connected. 3. The telephone line testing device as claimed in Claim 2, in which the second connecting means includes a plurality of second terminals to which a corresponding number of PABX input lines may be connected, there 205 being the same number of second terminals as there are first terminals, and with designated first and second terminals being associated with one another. 4. The telephone line testing device as claimed in Claim 3, in which 210 the first switch means includes a plurality of mechanically operable switches, each switch having a first contact connected to an associated first terminal, a second contact connected to the second terminal associated with said first terminal, a third contact connected to the test circuitry, and a contactor for connecting the first contact to either the second or third 21 5 contact. 5. The telephone line testing device as claimed in Claim 4, in which the ringing signal detection means is connected to all the third contacts of the first switch means. 220 6. The telephone line testing device as claimed in Claim 5, in which the test signal generating means is connected to all the third contacts of the first switch means via the second switch means. 7. The telephone testing device as claimed in any one of the preceding claims, in which the test circuitry has a lightning protection means. 8. A telephone line testing device for use with a PABX having a plurality of input lines, substantially as described herein with reference to the accompanying drawings. 9. A method of testing a telephone line connected to a PABX which includes disconnecting the PABX from the telephone line and connecting test circuitry to the telephone line; detecting the presence of a ringing signal on the telephone line by means of the test circuitry; and automatically supplying a test signal generated by a test signal generating means included in the test circuitry to the telephone line. 10. The method of testing a telephone line as claimed in Claim 8, in which the telephone line to be tested is accessed via the PABX, using another telephone line. 245 1 1 . A method of testing a telephone line connected to a PABX, substantially as herein described with reference to the accompanying drawings.

Inventors: VAN ROOYEN PETRUS CORNELIUS AL, VAN ROOYEN, PETRUS, CORNELIUS, ALBERTUS
Applicants: ROOYEN PETRUS CORNELIUS ALBERT, VAN ROOYEN, PETRUS, CORNELIUS, ALBERTUS
Application year: 2000
Main classification: H04M3
IPC codes: H04M3, H04M7, H04Q3