GB2333203A - Telephone testing handset - Google Patents

Abstract

A testing handset has a first input 31 for connection to a first element of a transmission line socket 9, a second input line 33 for connection to a second element of the transmission line socket 9 and a third input line 45 for connection to a bell line of the transmission line socket 9. The handset is provided with a ringing apparatus comprising a ringer 35 and a capacitor 37 in series therewith selectively connectable between the first input line 31 and the second input line 33 and means 47 for selectively connecting the third input line 45 to the first input line 31.

Description

TELEPRIONE TESTING HANDSET This invention relates to a telephone testing handset.

For testing purposes, telephone engineers are provided with special handsets which are used for testing lines and these handsets will test most of the operations of the lines.

Problems occur when it is necessary to test the ringing apparatus without the use of special extra equipment or the use of testing handsets with more than a "two" line input.

The present invention seeks to provide a modified two line testing handset which will enable the ringing operation to be tested.

According to the invention, there is provided a testing handset having a first input line for connection to a first element of a transmission line socket, a second input line for connection to a second element of the transmission line socket and a third input line for connection to a bell line of the transmission line socket, a ringing apparatus comprising a ringer and a capacitor in series therewith selectively connectable between the first input line and the second input line and means for selectively connecting the third input line to the first input line.

Preferably the means for selectively connecting the third input line to the first input line simultaneously disconnects the first input line from its input.

The invention will now be described in greater detail by way of example with reference to the drawings in which: Figure 1 is a simplified circuit diagram of a standard telephone connection; Figure 2 is a simplified circuit diagram of a standard testing handset currently in use; Figure 3 is a simplified circuit diagram similar to Figure 2 showing a testing handset modified to incorporate the invention; and Figure 4 is a simplified circuit diagram showing a testing handset connected for testing a line.

In the description, the general testing facilities for line testing will not be described since these are known and do not, as such, form any part of the invention.

Referring to Figure 1, the standard connection arrangements between the subscriber and its associated telephone exchange on a "two" line system 1 comprises two lines 3 and 5 known in the field as "B" and "A" lines which connect the exchange to the location of the telephone receiver 7. Down these two lines 3 and 5 travel not only voice, facsimile or like signals but also a ringing signal to alert the subscriber to that fact that a connection is being reqt tested. The subscriber's end ofthe line is provided with a socket 9 to which the telephone receiver 7 is connected. As will be seen, the socket 9 is provided with a number of connections, only three of which are shown here. These comprise a connection 11 for the "B" line, a connection 13 for the "A" line and a connection 15 for a "bell line" It also contains a bell shunt 17 and a spark gap 27.

While the ringing signal is transmitted down the two lines 3 and 5, the bell signal is produced by taking off a signal at the shunt 17 between the lines 3 and 5 and consisting a capacitor 19 and a resistor 21, the bell connection 23 being taken off between these two elements. The switches indicated at 25 and 26 are the switches actually located in practice within the receiver 7 and being operated together which are activated by removing the telephone handset from the instrument in order to answer it. Switch 25 connects line 3 to the handset while switch 26 shunts the ringing signal through shunt network 28. The making of these switches effectively forces all of the sound signals to pass through the handset in both directions. A safety device in the form of the spark gap 27 is provided to deal with lightning strikes or the like.

Figure 2 shows the ringing arrangements of a typical testing handset. It is used to connect to the incoming phone socket such as shown at 9 in Figure 1. Thus it has a connection 31 for connection to the line 3 and a connection 33 for the line 5. No connection is provided for the ringing socket 15 since the ringer 35 on the test set is provided with its own capacitor 37 and can thus detect ringing from the two main lines.

It also has a ring/audio switch 39, which in a test handset replaces the telephone cradle switch 25. Also provided on the handset is a disable switch 41 which is a double pole switch 43 which cuts off the test handset from the incoming line.

While such a test handset enables most of the functions of the telephone line to be checked, including ringing and voice use, it has one disadvantage, that is that no test can be performed of the ringing capacitor 19 at the incoming socket 9.

It is clearly desirable to enable this to be tested since, if it is faulty, it will not show up on the test but the subscriber's phone will continue not to ring. The same situation will also occur with subscriber's extension units if the bell connection to the extensions is faulty or not present. It is equally desirable to modify the existing type of test handset to have this facility with the minimum of change.

Figure 3 shows the modification proposed to overcome this problem which consists in providing a third input 45 to the handset and to replace one or both parts of the double pole switch 43 with a change over switch 47 which acts to changeover the incoming line from connection 31 to connection 45. In these circumstances, call termination by the handset can be achieved by again operating the switch 47.

Figure 4 shows the connection of the modified handset to the line. Thus once the test handset has been plugged in and with the switch 47 in the position shown, normal tests can be carried out. To test the capacitor 19, the changeover switch 47 is changed over so that the sole input from line 3 is through the capacitor. Then, if the exchange provides a ringing tone, the ringer 35 will only operate if the capacitor is in good order It will be appreciated that various modifications may be made to the above described embodiment without departing from the scope of the invention. For example, while the embodiment shown provides for minimum modification of the handset, nevertheless it is possible to provide the same facilities as well as redisconnect facility by retaining the switch 43 and making the changeover switch additional. Alternatively, one pole of the switch 43 could be retained, cutting off the line 5 when disconnection is required.

Claims (4)

1. CLAIMS 1. A testing handset having a first input line for connection to a first element of a transmission line socket, a second input line for connection to a second element of the transmission line socket and a third input line for connection to a bell line of the transmission line socket, a ringing apparatus comprising a ringer and a capacitor in series therewith selectively connectable between the first input line and the second input line and means for selectively connecting the third line to the first input line.
2. 2. A testing handset as claimed in claim 1, wherein the means for selectively connecting the third input line to the first input line simultaneously disconnects the first input line from its input.
3. 3. A testing handset as claimed in claim 1 or 2, wherein means are provided for selectively cutting off the handset from the input lines.
4. 4. A testing handset substantially as described herein with reference to figures 3 and 4 of the drawings.