GB2126840A - Method and apparatus for discriminating between relaying telephone sets - Google Patents

Abstract

A telephone call transfer apparatus (4, 4a, 4b) is provided in each of a plurality of offices (1, 1a, 1b). Each office is also provided with an incoming telephone set (B) and an outgoing telephone set (C), these telephone sets being connected to the telephone call transfer apparatus. The individual outgoing telephone sets are connected to at least one remote telephone set (D) provided in a particular office (2). The remote telephone set is provided with a discriminator (6-17, 25-27) for discriminating between the plurality of offices, through which a telephone call transmitted from an outside calling telephone set, for instance a public telephone set, is transmitted to the remote telephone set. The discriminator includes a hook-up detecting section (6), and is provided with a display section (11) including seven-segment light emitting diodes (17) for displaying line number and discriminated channel. <IMAGE>

Description

SPECIFICATION Method and apparatus for discriminating between relaying telephone sets This invention relates to a method and apparatus for discriminating between a plurality of relaying telephone sets.

An apparatus for automatically transferring telephone calls is commercially available as telephone call transfer apparatus. Fig. 1 shows a block diagram showing a prior art telephone call transfer apparatus.

Referring to the Figure, designated at 1 is an office, in which the transfer apparatus is installed, and at 2 an office at which one from the office 1 is on a trip. Designated at A is a calling telephone set which may be a public telephone set. In the office 1, an incoming telephone set B and an outgoing telephone set C are provided. Designated at D is a remote telephone set provided in the office 2.

Designated at 3 is a telephone circuit from the calling telephone set A to the incoming telephone set B. The telephone call transfer apparatus, designated at 4, is connected between the incoming telephone set B and outgoing telephone set C. Designated at 5 is a telephone circuit from the outgoing telephone set C to the remote telephone set D.

Usually, a clerk is present in the office 1, and when a bell of the incoming telephone set B is operated due to a telephone call from the outside telephone set A such as a public telephone set, the clerk may unhook the handset of the telephone set B to effect communication with the telephone set A. However if the clerk is out of the office 1 so that nobody is in the office 1, the communication usually cannot be obtained. In the system of Fig. 1, however, when a telephone call is transmitted from the calling telephone set A to the incoming telephone set B through the telephone circuit 3 while no one is in the office 1, the telephone call transfer apparatus 4 detects the call and holds the outgoing telephone set such that it is capable of speech transmission (i.e., holds the handset of the telephone set C in the same state as the unhooked state though it is not actually unhooked).Also, the apparatus 4 calls the remote telephone set D in the office 2, to which the clerk is on a trip, the remote telephone set D being registered in a memory of the central office, through the telephone circuit 5 of the outgoing telephone set C. In this case, by unhooking the handset of the telephone set D, the handset of the incoming telephone set B is automatically rendered into the same state as it is unhooked, thus making it possible to effect direct communication between the calling telephone set A and the remote telephone set D through the incoming and outgoing telephone sets B and C. Fig. 2 shows an example of the actual use of the telephone call transfer apparatus as described above.Here, an office 1 which is in New York, for instance, an office 1 a which is in Chicago, for instance, and an office 1 b in Washington, for instance, are provided with respective telephone call transfer apparatus such that all telephone calls after the business time is over, for instance at 7:00 p.m. are transmitted to an office 2 which is in Boston, for instance. However, it has been impossible to determine which office among the offices in New York, Chicago and in Washington a telephone call is transmitted to the office in Boston through.

An object of the present invention is to permit instantaneous discrimination of one of a number of telephone call transfer apparatus installed in difference places, through which office a telephone call is transferred, thus promoting the business efficiency.

Another object of the present invention is to provide a discriminator of the type mentioned above, which permits visual discrimination.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a block diagram showing a telephone call transfer apparatus; Fig. 2 is a view showing an example of use of a plurality of telephone call transfer apparatus installed in different places; Fig. 3 is a schematic representation of a circuitry of an embodiment according to the present invention; Fig. 4 is a schematic representation of a circuitry of a different embodiment of the present invention; Fig. 5 is a circuit diagram showing a hook-up detecting section; Fig. 6 is a circuit diagram showing a master clock discrimination signal sync coincidence circuit; and Fig. 7 is a circuit diagram showing the detailed circuit construction of the circuitry according to the present invention.

Referring now to Fig. 3, designated at 1 is an office in New York, for instance, at 1 a is an office in Chicago, for instance, and at 1 b is an office in Washington, for instance. Designated at 2 is an office in Boston. Designated at A is a calling telephone set, for instance a public telephone set in the suburbs of New York. The offices 1, 1 a and 1 b are each provided with an incoming telephone set B and an outgoing telephone set C. Designated at D is the remote telephone set in the office in Boston. The calling telephone set A is connected to the individual incoming telephone sets B through respective telephone circuits 3, 3a and 3b. The offices 1, 18 and 1 b are provided with respective telephone call transfer apparatus 4, 4a and 4b which are connected to the associated incoming and outgoing telephone sets B and C.

The individual outgoing telephone sets C are connected to the remote telephone set D in Boston through respective telephone circuits 5, 5a, Sb. Designated at 6 is a hook-up detecting section, which is coupled through a discrimination signal coupling transformer 7 to a discrimination signal decoding IC 8. The discrimination signal decoding IC 8 is connected to a master clock discrimination signal sync coincidence circuit 9, which is in turn connected to a channel memory 10. The channel memory 10 is connected to a display section 11 for displaying line number and discriminated channel. The hook-up detecting section 6 is also directly connected to the channel memory 10 through a separate signal line 27.

Designated at 12 is a master clock generating section, which is connected to a master clock line data coincidence circuit 13, a channel display decoder 14 and a write pulse trigger IC 1 5. The write pulse trigger IC 1 5 is connected through a memory write pulse generating section 1 6 to the channel memory 10. Designated at 17 are sevensegment light-emitting diodes for the display.

Fig. 4 shows an embodiment of the invention, which includes a plurality of remote telephone sets D which are the same as the remote telephone set provided in the office in Boston in case of Fig. 3. In this embodiment, hook-up detecting sections 6 are provided in number corresponding to the number of the telephone sets D, and an incoming circuit control section 1 8 is provided between the individual hook-up detecting sections 6 and coupling transfoerm 7.

While in the case of Fig. 3 the signal line 27 is connected to the hook-up detecting section 6, in the case of Fig. 4 the line 27 is connected to the incoming circuit control section 1 8 to control the plurality of telephone sets D.

Fig. 5 shows the details of the hook-up detecting section 6. The section includes a rectifying diode 19, a zener diode 20 and a photocoupler 21. Designated at 22 is an output terminal. Terminals L1 and L2 are connected in parallel with respect to the remote telephone sets D. While there is no telephone call transmitted to any of the remote telephone sets D in Fig. 5, that is, while the hook-up section 6 is in a stand-by state, a certain voltage prevails at the output terminal 22 of the photo-coupler 21 due to a preset voltage of the zener diode 20. When the handset of one of the telephone sets D is unhooked in response to a telephone call transmitted to that telephone set, the voltage across the zener diode 20 becomes lower than the preset voltage due to a voltage drop produced across the circuit resistance.As a result, the voltage at the output terminal 22 of the photocoupler 21 vanishes due to the action of the photo-coupler 21.

Fig. 6 shows the detailed construction of the master clock discrimination signal sync coincidence circuit 9. The circuit 9 includes exclusive OR gates. Designated at 24 is an output terminal. While there is no telephone call transmitted to any of the telephone sets D, that is, in a stand-by state of the circuit 9, there is no voltage at the output terminal 24. When a telephone call is transmitted to a telephone set D, a discrimination signal sound consisting of a multiplex frequency DTMF signal, indicating the transfer of a telephone call, is heard from the telephone set D. The discrimination signal sound is converted by a multiplex frequency signal decoding IC into a 4-bit binary code. This code and a 4-bit binary code generated from the master clock generating section 12 are coupled to the exclusive OR gates 23.When both the 4-bit binary codes coincide, an output appears at the output terminal 24. Designated at 25 in Fig. 3 is a circuit control section, and at 26 a relay switch.

The operation will now be described.

When one at the calling telephone set A calls the incoming telephone set B in, for instance, the office 1 in New York while the offices 1, 1 a and 1 b in New York, Chicago and Washington respectively are closed, a remote telephone set D in the office 2, for instance in Boston, is called through the associated outgoing telephone set C on the basis of the well-known principles of transfer.

At this time, by unhooking the handset of the remote telephone set D a lower voltage than before is generated at the plus terminal of the rectifying diode 19 in the hook-up section 6. As a result, the primary side light-emitting diode in the photo-coupler 21 is turned off by the action of the zener diode 20, thus turning off the transistor in the photo-coupler 21 so that the output at the output terminal 22 vanishes. With the vanishing owt the output, a negative signal is applied to the circuit control section 25 so that the section 25 turns on the relay switch 26 in Fig. 3, causing a DTMF signal to be transmitted through the discrimination signal coupling transformer to the discrimination signal decoding IC.The telephone call transfer apparatus 4, 4a and 4b in the respective offices 1, 18 and 1 b in New York, Chicago and Washington are allotted with different outgoing DTMF signals. The discrimination signal decoding IC discriminates whether there is a display key signal. If a display key signal is detected, it permits action to read out a channel signal, thus discriminating the DTMF signal and converting the frequency of the discriminated DTMF signal into a digital signal.

The exclusive OR gates 23 shown in Fig. 3 takes synchronization of this digital signal and a digital signal produced from the master clock generating section 12, and only the synchronous signal is provided from the output terminal 24. This signal is written in the channel memory 10 to be memorized until the handset is hooked again. The signal is also coupled to the display section 11 for displaying the line number and discriminated channel. Thus, the line number is displayed by seven-segment light-emitting diodes 17 for the pertinent channel. It will be seen that the office, through which the outside telephone call is transferred, can be visually known together with the line number.

Meanwhile, the master clock generating section 12 is always producing a synchronization signal for synchronization with the input DTMF signal. With this signal the channel display decoder 14, master clock line data coincidence circuit 13 and write pulse trigger IC 1 5 are monitored so that synchronization may be established only when a P.B. tone is converted into a digital signal.

The operations of the embodiment of Fig. 4, which includes a plurality of remote telephone sets D, other than that described above, are the same as in the embodiment of Fig. 3 In the prior art case of Fig. 2 as described earlier, in which the office 1 in New York, office 1 a in Chicago and office 1 b in Washington are provided with respective telephone call transfer apparatus and all the telephone calls calling these offices after the business time is over, for instance after 7:00 p.m., are transferred to a particular office such as the office 2 in Boston, it has been impossible to discriminate which one of these offices a telephone call is transmitted through.

According to the present invention, the office through which a telephone call is transmitted can be visually known, as has been described in the foregoing.

Claims (7)

1. A method of discriminating between relaying telephone sets in a plurality of offices each of which is provided with an incoming telephone set responsive to a telephone call from a calling telephone set, an outgoing telephone set connected to a remote telephone set provided in a particular office, and a telephone call transfer apparatus connected to said incoming and outgoing telephone sets, said method comprising providing the remote telephone set with a discriminator to determine which one of said offices a telephone call is transmitted through.

2. An apparatus for discriminating between relaying telephone sets in a plurality of offices each of which is provided with an incoming telephone set responsive to a telephone call from a calling telephone set, an outgoing telephone set connected to a remote telephone set provided in a particular office, and a telephone call transfer apparatus connected to said incoming and outgoing telephone sets, the discriminating apparatus comprising a discriminator which is provided for said remote telephone set and which includes seven-segment light-emitting diodes for displaying an identification of the one of said offices through which a telephone call is transmitted.

3. An apparatus for discriminating between relaying telephone sets in a plurality of offices each of which is provided with an incoming telephone set responsive to a telephone call from a calling telephone set, an outgoing telephone set connected to a remote telephone set provided in a particular office, and a telephone call transfer apparatus connected to said incoming and outgoing telephone sets, the discriminating apparatus comprising a hook-up detecting section to be coupled to said remote telephone set, a discriminating signal decoding IC coupled to said hook-up detecting section through a discrimination signal coupling transformer, a master clock discrimination signal synchronization coincidence circuit connected to said discrimination signal decoding IC, a channel memory connected to said master clock discrimination signal synchronization coincidence circuit, and a display section connected to said channel memory for displaying line number and discriminated channel, said hook-up detecting section being also connected to said channel memory, and said master clock generating section being also connected to a master clock line data coincidence circuit, a channel display decoder, and write pulse trigger IC.

4. An apparatus as claimed in Claim 3 or Claim 4, and comprising a plurality of remote telephone sets each connected to a plurality of relaying telephone sets.

5. A method of discriminating between relaying telephone sets in a plurality of offices, substantially as hereinbefore described with reference to Figures 3 to 7 of the accompanying drawings.

6. Apparatus for discriminating between relaying telephone sets in a plurality of offices, substantially as hereinbefore described with reference to Figures 3, 5, 6 and 7, or to Figures 3, 5, 6, and 7 as modified by Figure 4, of the accompanying drawings.

7. The features herein described, or their equivalents, in any patentably novel selection.