GB2237957A - A device for switching telephone calls to a facsimile machine or to a telephone set - Google Patents

Abstract

A modem (5) samples, from line (1), signals representing the signals conveyed by said line (1) without interfering with them. A micro-controller (6) controls a switch (2) in response to the signals samples so that, in the absence of a call, the line (1) is connected to a fax machine (4). If a call is followed by protocol signals coming from a distant fax machine, the micro-controller leaves the line (1) connected to the fax machine (4). If not, it controls a ringing generator (7) of the telephone set (3) and connects the line (1) to it, if the receiver has been unhooked. The invention permits a subscriber to use the same telephone line for faxes and conversations without having to carry out switching operations. <IMAGE>

Description

DESCRIPTION "h DEVICE FOR SWITCHING TELEPHONE CALLS TO A FACSIMILE MACHINE OR TO A TELEPHONE SET" The present invention relates to a device for switching calls on a telephone line to a fax machine or to a telephone set.

Such a device permits the use of a single telephone line for receiving conventional telephone calls, that is to say in which the exchange is vocal, and telephone calls relative to the transmission of documents or faxes, without having to manually connect the line to one or the other of the apparata depending on the nature of the call received.

Devices of the type defined above are already known which are based on the fact that some fax machines are provided for transmitting, bursts of a signal at 1100 Hz prior to any exchange in the course of a communication in which they are the callers.

Thus, when a signal coming from such a fax machine ends up at a conventional telephone set, the person who picks up the receiver knows that he or she is dealing with a fax machine and not another person.

Existing switching devices use this 1100 Hz signal to recognise the nature of the call and to consequently switch it to the right apparatus.

Thus, these known devices, in response to ringing coming from the line; take the call and attempt to recognise, for several seconds, a burst of 1100Hz transmitted by the possible calling fax machine. Thus they produce a ringing to the receiving fax machine and pass the line over to it as soon as the receiver is lifted. If no 1100 Hz signed is recognised, they produce a ringing to the telephone set and pass over the line to it as soon as the receiver is lifted. The 1100 Hz signal is usually detected using a filter.

However, these known devices are not very reliable because the 1100 Hz signal is not transmitted by all the calling fax machines, and because a person calling could emit sound waves comprising energy in the region of 11000Xz > It is an object of the present invention to provide a device for switching calls to a fax machine or to a telephone set, which substantially overcomes these difficulties.

In accordance with the present invention, there is provided a device for switching calls on a telephone line, comprising connection means for connecting said line either to at least one first apparatus provided for receiving calls coming from a person, or to at least one second apparatus provided for receiving calls coming from an apparatus of the telecopier or fax transmission type, control means for controlling said connection means, which is sensitive tb the nature of the calls on said line, and noninterfering sampling means for sampling from said line, signals representing the signals carried by said line, recognition means for recognising, amongst the sampled signals, signals representing the protocol signals transmitted by a calling distant apparatus of the telecopier type in response to protocol signals transmitted by said second apparatus when it receives a call, said control means controlling, in the absence of a call, and in the presence of a call followed by recognition of said signals representing the protocol signals, the connection of said line to said second apparatus, and, in the presence of a call not followed by recognition of said signals representing the protocol signals, the connection of said line to said first apparatus.

In the device of the present invention, all the incoming calls end up at the fax machine, because, in the absence of a call, the line is systematically connected to it. If an incoming call comes from a distant fax machine, the exchange protocol between the distant fax machine and the local fax machine is started just as soon as if the line were dedicated exclusively to the local fax machine. Thus, thanks to the monitoring of the signals on the line which is carried out by the sampling means and the recognition means, the characteristic protocol signals of the distant calling fax machine may be detected, which is formal proof that the caller is a fax machine. In this case, the control means leaves the line connected to the fax machine so that a facsimile-type exchange can take place.If, however, the incoming call comes from a person, the fax machine protocol cannot start, despite the protocol signals, in this case an identification signal transmitted several times by the local fax machine. In this case, the line is connected to the conventional telephone set.

The device of the present invention is thus particularly reliable, and, moreover, it is completely transparent to facsimile-type exchanges, since the line is normally connected to the fax machine.

In a preferred embodiment, the device is provided with ringing means to make said first apparatus ring, and means for detecting whether an apparatus is off the hook for detecting whether said first apparatus is off the hook, and, in the presence of a call not followed by recognition of said signals representing the protocol signals, said control means causing said first apparatus to ring, and connecting said line to said first apparatus in response to detection of said first apparatus being off the hook.

In this case, it is not necessary for the fax machine to be provided with its own alarm bell for warning the subscriber of an incoming call, since, if said call is intended for the subscriber, the telephone set rings. Moreover, and above all, the subscriber does not have to watch the fax machine to see for whom the incoming call is in fact intended, which is the case if'the line is immediately connected to the conventional telephone set when the protocol signals are not recognised.

Advantageously, said control means stops said ringing means and frees said line, following a determined ringing time, not followed by detection of said first apparatus being off the hook.

Thus, the calling party does not end up waiting too long, ignorant of what has become of his call.

Advantageously again, there are provided means for transmitting on said line, signals for informing a possible caller that said first apparatus is in the process of ringing.

These signals are, for example, known return ringing signals, or even artificial voice signals giving clear information.

In order to render the device transparent to outgoing calls, that is to say, calls transmitted by a subscriber who has the switching device installed, the device is further provided with means for detecting whether an apparatus is off the hook, and means for recognising an exchange between two apparata of the telecopier type, said control means connecting said line to said first apparatus in response to detection of the apparatus being off the hook, unless an exchange between two apparata of the telecopier type is taking place.

Advantageously, there is provided means for sending a ringing signal to said second apparatus, and said control means, in response to a command from the user of said first apparatus, controlling the despatch of a ringing signal to said second apparatus, as well as the connection of said line to said second apparatus in order to permit, following a vocal cwrmnication, a fax-type communication during the sane telephone call.

In a further embodiment, there are provided a plurality of said first apparata, and said control means, which, in response to the commands of the users, control the connection of said line to one or the other of said first apparata.

By way of example only, specific embodiments of the present invention will now be described, with reference to the accompanying drawings, in which: Fig. 1 shows a block diagram of one embodiment of a switching device of the present invention, and Fig. 2 shows a further embodiment of a switching device.

As shown in Fig. 1, the switching device of the present invention is intended to be inserted between a telephone line 1 and, in this case, two apparatuses 3 and 4, for switching calls on line 1 to one or the other of the apparatuses 3 and 4, depending on the nature of these calls.

The apparatus 3 is, in this case, a telephone set, or, possibly, a telephone answering set. In a general way, it is an apparatus provided for receiving calls coming from a person.

The apparatus 4 is, in this case, a fax machine, but it could be a secondary apparatus. In a general way, it is an apparatus provided for receiving calls coming from another fax machine.

A three-position controllable switch 2 permits the line 1 to be connected either to the telephone set 3, the fax machine 4, or to the transmission access of a modulator-demodulator or modem 5. The switch 2 is provided with a control input receiving a connection control signal CR.

In addition to the transmission access connected to the switch 2, the modem 5 is provided with a receiving access connected to line 1 of a data output delivering a signal S and a data input receiving a signal E. The modem 5 is of the known V21 type. The signal S represents the data demodulated relative to a possible modulated signal received by the modem 5 on its reception access, and, in response to a data signal E, the modem 5 transmits a modulated signal on its transmission access.It should be noted that the modem 5 is disposed such that its reception access presents to the line 1 an increased impedance in order not to interfere with the normal function of the line 1, and that, when this line 1 is connected to one of the apparatuses 3 or 4, the modem 5 permits sampling of signals representing those conveyed by the line 1, in one direction or the other, without interference with the functioning of the line 1 and the apparatus to which it is connected. It can be said that the modem 5 monitors or eavesdrops on the line 1.

A micro-controller 6 is provided with a data input receiving the signal S, two binary inputs receiving, respectively, a first signal DD for detecting when an apparatus is off the hook and a second signal DD' for detecting when an apparatus is off the hook, a data output delivering the signal E, and three binary outputs delivering, respectively, the connection control signal CR, a ringing control signal CS and a signal CAS for controlling switching of the ringing. A circuit 7 for generating a ringing signal and detecting when an apparatus is off the hook is provided with a binary input receiving the ringing control signal CS, a binary output delivering the first signal DD for detecting when an apparatus is off the hook, and a bi-directional access.The circuit 7 is a circuit of the known type which usually performs the functions of generating a ringing signal and of detecting when an apparatus is off the hook in telephone exchanges. A circuit 7' for detecting when an apparatus is off the hook, which delivers a second signal DD' for detecting when an apparatus is off the hook, is connected to the input of the apparatus 4.

A three-position controllable switch 8 permits the connection of the bi-directional access of the circuit 7 either to the telephone set 3 or the fax machine 4, or allows the bi-directional access to remain isolated. The switch 8 is provided with a control input receiving the signal CAS for controlling switching of the ringing.

The device described above operates as follows.

Because of the modem 5, to which it is connected, the micro-controller 6 is able to recognise the signals on the line 1. In the absence of signals on said line 1, the micro-controller 6 controls the switch 2 so that the line is connected to the fax machine 4. Thus, all the incoming calls are systematically switched to the fax machine 4.

The latter is arranged, as are all fax machines, to transmit, as soon as it receives a call, a protocol signal comprising, notably, in this case, a digital identification signal DIS as defined in Recommendation T.30 of the International Consultative Committee for the Telegraph and the Telephone, or C.C.I.T.T.

Thus, any call entering on line 1 is followed by the transmission of a digital identification signal DIS on this line. If the call comes from a distant fax mahine, the latter should respond in particular to the signal DIS with a corresponding protocol signal, in this case, one of the following protocol signals defined in Reca8pmoendation T.30 of the C.C.I.T.T.: - non-standard facilities set-up signal NSS, - transmitting subscriber identification signal TSI, - digital command signal DCS, - non-standard facilities command signal NSC, - called subscriber identification signal CIG, - digital transmit command signal DTC.

The micro-controller 6 is arranged to recognise, amongst the signals sampled on the line 1, preceding protocol signals transmitted by the distant fax machine, in response to the digital identification signal DIS. If the call is followed by a recognition of these protocol signals, it means that the call comes from a fax machine, and the micro-controller 6 leaves the line 1 connected to the fax machine 4.

If the call is not followed by a recognition of protocol signals coming from a distant fax machine, when the fax machine 4 has repeated the digital identification signal DIS three times, the microcontroller 6 connects the line 1 to the telephone set 3.

To do this, the micro-controller 6 controls the circuit 7 by way of the signal CS such that it generates a ringing signal, and, by way of the signal CAS, the switching of this ringing signal to the telephone set 3. The telephone set 3 then rings and, if the subscriber is present, he unhooks the receiver.

This unhooking of the receiver is detected by the circuit 7, and the micro-controller 6, warned by the signal DD, thus controls the switch 2 to connect the line 1 to the set 3. While the set 3 is ringing, the micro-controller controls, by way of the signal CR, the connection of the line 1 to the transmission access of the modem 5. The latter is not at high ippedance, but at normal impedance, for example 600sue, and maintains the continuous current loop of the line.

The micro-controller controls, by way of the signal E, the transmission of a discontinuous carrier simulating a return ringing tone. Alternatively, a speech synthesiser may transmit an explanatory vocal message.

If the subscriber is absent, there is no detection of the apparatus being off the hook, the micro-controller 6 then stops the ringing after a determined period and frees the line 1.

In order for the subscriber to be able to call someone using the telephone set 3 without having to manually connect to said set 3, line 1, which is normally connected to the fax machine 4, the microcontroller 6 is arranged to connect the line 1 to the set 3 as soon as the signal DD indicates that the set 3 is off the hook, and not as a result of the set 3 ringing. Bowever, as it is possible that a fax exchange may thus be taking place between the fax machine 4 and a distant fax machine, the microcontroller 6, which can recognise such an exchange on the line 1 thanks to the detector 7', only connects the line 1 to the set 3 in the absence of such an exchange, so as not to interrupt the fax transmission.

In this case, the micro-controller 6 is also arranged to receive, in the course of a call between the subscriber and a caller, by way of the set 3, a command from the subscriber intended to obtain, without interruption of the telephone call, connection of the line 1 to the fax machine 4 for a fax exchange following the vocal exchange.

The command is given, for example, by the subscriber, by dialling on the multi-frequency dial (dual tone modulation frequency, D.T.M.F.) of the set 3, a predetermined number, for example, 7, which corresponds to the transmission of a signal composed of two predetermined frequencies. The microcontroller 6 detects this command by way of the modem 5, which is provided to this end, with suitable filters, and controls by way of the signal CS the generation of a ringing signal by the circuit 7, as well as, by way of the signal CAS, the switching of this ringing signal to the fax machine 4. Everything is effected as if the fax machine 4 were being called. It is "taken off the hook", and this is detected by the circuit 7, and the micro-controller 6, in response to the signal DD, then controls the connection of the line 1 to the telecopier.Of course, the caller with whom the subscriber has made an agreement, does the same at his end in order to connect his fax machine to the line 1. The distant fax machine thus receives the protocol signal of the fax machine 4, and everything is effected as if the distant fax machine were the calling fax machine. There is an exchange of protocol signals followed by the facsimile exchange.

Fig. 2 shows a variant of the switching device of Fig. 1, for which variant, it is possible to connect two telephone sets 3 and 3' in place of one. A fourposition switch 2' replaces the switch 2, and a switch 8' having three active positions and two inactive positions replaces the switch 8.

The modem 5 and the circuit 7 are unaltered, whereas the micro-controller 6' is arranged, on one hand, to perform the functions of the micro-controller 6, and on the other hand, to control the connection of the line 1 to the set 3, or to the set 3', in response to commands from the user of the set 3' or the set 3, respectively. As has already been described, these orders may be formed by selecting a number on the keyboard of the corresponding set in such a way as to inform the micro-controller 6 that it is desired to move to the other set.

Of course, it would be possible to provide means for the connection of more than two telephone sets 3 and 3', as well as putting line 1 on standby and so on. Such variants are of course within the scope of a person skilled in the art, as is the programming of the micro-controller 6 from the functions which it must perform and which have been described above.

If, in the above, described device, the circuits 7 and 8 provide certain advantages, they are not absolutely essential, and it is possible to envisage, in a very simplified version, implementing the invention without these circuits.

Claims (8)

1. A device for switching calls on a telephone line, comprising connection means for connecting said line either to at least one first apparatus provided for receiving calls coming from a person, or to at least one second apparatus provided for receiving calls coming from an apparatus of the telecopier or fax transmission type, control means for controlling said connection means, which is sensitive to the nature of the calls on said line, and non-interfering sampling means for sampling from said line, signals representing the signals carried by said line, recognition means for recognising, amongst the sampled signals, signals representing the protocol signals transmitted by a calling distant apparatus of the telecopier type in response to protocol signals transmitted by said second apparatus when it receives a call, said control means controlling, in the absence of a call, and in the presence of a call followed by recognition of said signals representing the protocol signals, the connection of said line to said second apparatus, and, in the presence of a call not followed by recognition of said signals representing the protocol signals, the connection of said line to said first apparatus.

2. A device as claimed in claim 1, further comprising ringing means to cause said first apparatus to ring, and means for detecting whether an apparatus is off the hook for detecting whether said first apparatus is off the hook, and, in the presence of a call not followed by recognition of said signals representing the protocol signals, said control means causing said first apparatus to ring, and connecting said line to said first apparatus, in response to the detection of said first apparatus as being off the hook.

3. A device as claimed in claim 2, wherein said control means stops said ringing means and frees said line following a predetermined ringing time, not followed by detection of said first apparatus as being off the hook.

4. A device as claimed in either of claims 2 or 3, in which there are provided means for transmitting, on said line, signals for informing a possible caller that said first apparatus is in the process of ringing.

5. A device as claimed in any of claims 1 to 4, further having means for detecting whether an apparatus is off the hook for detecting whether said first apparatus is off the hook, and means for recognising an exchange between two fax machines said control means connecting said line to said first apparatus, in response to detection of the apparatus as being off the hook, unless an exchange between two fax machines is taking place.

6. A device as claimed in any of the preceding claims comprising means for sending a ringing signal to said second apparatus, said control means, in response to a command from the user of said first apparatus, controlling the despatch of a ringing signal to said second apparatus, as well as the connection of said line to said second apparatus, in order to permit, following a vocal exchange, a facsimile exchange during the same telephone call.

7. A device as claimed in any of the preceding claims comprising a plurality of said first apparata, and, in response to the commands of the users, said control means controlling the connection of said line to one or the other of the said first apparata.

8. A device for switching the telephone calls to fax machines or to a telephone set substantially as hereinbefore described, with reference to the accompanying drawings.