GB2242336A

GB2242336A - Unit selects facsimile or telephone according to tone signal on incoming line

Info

Publication number: GB2242336A
Application number: GB9006372A
Authority: GB
Inventors: Richard Bell; R John S Perkins
Original assignee: DATA MEMORIES PLC; TELYCOM LINKLINE Ltd
Current assignee: DATA MEMORIES PLC; TELYCOM LINKLINE Ltd
Priority date: 1990-03-21
Filing date: 1990-03-21
Publication date: 1991-09-25
Also published as: GB9006372D0

Abstract

A line switching unit 10 has an input for connection to a telephone line L a first output port P1 for connection to a facsimile machine FM, a second port for connection to a telephone handset TH, and a detector 17 arranged to respond to a predetermined DTMF tone on the line L in order to switch the incoming line to the first port P1. Either the caller or the local user may initiate the DTMF tone to switch the incoming line to the facsimile machine when the calling machine is being operated in manual mode. The unit also has a detector 16 which responds to the characteristic tone transmitted by a calling facsimile machine when operated in automatic mode, to switch the incoming line to the port P1. Instead a modem M may be connected to port P1 and the unit includes a detector 18 which responds to the characteristic tone transmitted by the calling equipment when the unit picks up, to switch the incoming line to port P1. <IMAGE>

Description

LINE SWITCHING UNIT This invention relates to a line switching unit for connection to a telephone line and arranged to switch the line to appropriate output ports of the unit.

There is often a need for a telephone line to be used alternatively with a telephone handset or with a facsimile machine. Some automatic line switching units have been proposed for this use but they have suffered various drawbacks, including reliance upon voice recognition chips. We have now devised an improved line switching unit which overcomes these drawbacks.

In accordance with this invention, there is provided a line switching unit which has an input for connection to a telephone line, a first output port for connection to a facsimile machine, a second output port for connection to a tel-ephone handset, and a detectqr arranged to respond to a predetermined DTMF tone on the line in order to switch the incoming line to the first output port.

Thus, if a caller wishes to send a fax transmission by manual rather than automatic mode, once the line 5|ff7 switching unit at the receiving party picks up, the caller can transmit the predetermined DTMF tone in order to switch the line to the fax machine at the receiver. The DTMF tone can be generated by the caller pressing an appropriate code on the keypad of his handset or fax, e.g. the code #1. Alternatively the receiving user can generate this tone on his own handset.

Preferably the line switching unit includes a detector which responds to the fax tone normally transmitted by a fax machine in automatic mode immediately after the receiving equipment picks up. Thus if the line switching unit receives a call from a fax machine in automatic mode, it detects the characteristic fax tone immediately after picking up, and responds to this by switching the incoming line to the fax machine.

An answering machine and normal telephone handset may be connected to the second output port of the line switching unit. If a caller wishes to transmit a fax by manual mode, the unit will initially route the line to that port, because the characteristic fax tone will not be present. If the receiving party fails to respond using the handset, the telephone answering machine will respond in the usual manner and relay its recorded message. Preferably this recorded message includes the advice that if the caller wishes to transmit a fax, he should press the appropriate code (e.g. Çtl) on his keypad. When the caller does this, the line switching unit responds and switches the line to the fax port.

Preferably the line switching unit has an output port for connection of a modem, and includes means for detecting a characteristic modem tone which is transmitted from the calling equipment when the receiving unit picks up. When the line switching unit detects this characteristic modem tone, it switches the incoming line to the modem output port. Preferably the first output port of the unit may be used alternatively for a fax machine or for a modem.

Also in accordance with this invention, there is provided a line switching unit which has an input for connection to a telephone line, a first output port for connection to a modem, a second output port for connection to a telephone handset, and a detector arranged to switch the incoming line to the first output port in response to a characteristic modem tone transmitted on the line from the calling equipment when the unit picks up.

An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIGURE 1 is a block diagram of a line switching unitin accordance with this invention; and FIGURE 2 is a flow diagram for use in explaining the manner in which the line switching unit operates.

Referring to Figure 1, there is shown an automatic line switching unit 10 which has an input for connection to a single telephone line L, a first output port Pl and a second output port P2. The first output port PI is for connection to a facsimile machine FM or alternatively a modem M. The second output port P2 is for connection to a telephone handset TH and also preferably an answering machine AM.

The line switching unit 10 includes a ring detector 13 and a switch 11 for sensing and connecting the line in the event of an incoming call. Switch 12 is provided to connect the line alternatively to port P1 or port P2. A manual switch S controls switch 12, but four detectors 14, 16, 17, 18 are also included in the unit for controlling switch 12. A voice synthesiser 15 and a telephone ringing circuit 19 are used when there is an incoming voice call. Detector 16 detects the characteristic fax tone which is placed on the line by a transmitting machine in automatic mode once the receiving unit picks up. Detector 16 responds to such a tone to switch the line to the output port P1.

There is also a detector 17 which will detect a predetermined dual tone multi-frequency (DTMF) signal (corresponding two #1) on the line, again to switch the line to port P1. There is a detector 18 which responds to the characteristic modem tone placed on the line by the transmitting equipment once the receiver picks up: if this is detected the line is again switched to port P1. Preferably the detector 18 is able to detect the characteristic tone for V21, V22 and V23 type modems.

The detector 14 will, in the absence of fax or modem tones, activate the voice synthesiser 15 to replay a preprogrammed message such as "please hold, while your call is being connected", and will also activate the telephone ringing circuit 19 switching the line to port P2.

Whilst the telephone handset TH is ringing a further message of "please hold" is replayed at intervals by the voice synthesiser 15. If after say 24 rings the receiver does not pick up his telephone handset TH, the caller will be informed by the voice synthesiser 15; "sorry, we are unable to connect your call, please try later", afterwards the line will be disconnected automatically by opening switch 11.

The operation of the line switching unit is shown in outline in Figure 2, which is a schematic flow diagram. At step 100 the unit picks up upon receipt of an incoming call on the line L. At step 102 the detectors 16, 18 detect for the characteristic fax or modem tones: if either of these tones is detected, the line is switched at step 104 to the output port P1, to which the fax machine or modem is connnected. If no such tone is detected, the call is routed at step 106 to the output port P2 for the telephone handset or answering machine. If now the DTMF tone iE1 is detected by detector 17 at step 108, the line is switched at step 110 to port P1 for the fax machine. Otherwise step 112 monitors the manual switch S and if this is operated, then at step 114 the line is switched to port P1. When line disconnect is detected at step 116, the line is disconnected, otherwise the sub-routine continues to monitor for the DTMF tone or operation of the manual switch S.

Claims

1) A line switching unit which has an input for connection to a telephone line, a first output port for connection to a facsimile machine, a- second output port for connection to a telephone handset, and a detector arranged to respond to a predetermined DTMF tone on the line in order to switch the incoming line to the first output port.

2) A line switching unit as claimed in claim 1, further including a detector which responds to a tone transmitted by a facsimile machine in automatic mode, to switch the incoming line to the first output port.

3) A line switching unit as claimed in claim 1 or 2, in which the first port or a further port is connectable to a modem, and further comprising a detector which responds to a characteristic modem tone received over the telephone line, to switch the incoming line to the first or further port.

4) A line switching unit which has an input for connection to a telephone line, a first output port for connection to a modem, a second output port for connection to a telephone. handset, and a detector arranged to switch the incoming line to the first output port in response to a characteristic modem tone transmitted on the line from the calling equipment when the unit picks up.

5) A line switching unit substantially as herein described with refernce to the accompanying drawings.