GB2303272A - Telephone network - Google Patents

Abstract

In a telephone having duplex lines capable of receiving voice and fax transmissions, call waiting services are cancelled or suppressed during fax transmissions. This is required for making full use of call waiting services because on duplex lines, the usual call waiting service arrangement will corrupt fax transmissions.

Description

TELEPHONE NETWORK The invention relates to telephone networks.

The invention relates more particularly to telephone networks having duplex or multiplex lines in which more than one telephone number is allocated to a single line.

With such lines it is known to provide a call-waiting signal if a third party dials either of the numbers of the line. This is normally provided by tone signals interposed on the line while the existing call is appropriately and briefly disconnected. As it is possible for one or both the telephone numbers to be used for transmitting fax data in addition to voice or instead of voice, interruption of the call and application of time signals will corrupt any fax message.

It is an object of the present invention to overcome this problem.

According to the invention, there is provided a multiplex telephone network having a call-waiting service for one or more lines in which some of the numbers allocated to such lines are for receiving fax transmissions, including a cancel call-waiting service that responds to transmission of facsimile data to inhibit application of a call waiting service to the line during fax transmissions.

The cancel call-waiting service may be initiated by any incoming signal to any numbers of each line that has been pre-allocated for receiving fax transmissions.

The network can be arranged to provide signals to identify to the caller that the called number has a fax marker, and the cancel call waiting service then responds to receipt of such identifying signals from the called number.

The cancel call waiting service for the called line may be automatically initiated when calls are made from a caller that has a cancel call waiting service, or whenever the leading digits of the called number have a certain fixed pattern.

Telephone networks having cancelling call waiting services according to the invention will now be described by way of example with reference to the accompanying flow chart drawings in which: Figure 1 is for incoming fax calls; Figures 2A and 2B are for outgoing fax calls; and Figures 3A and 3B are for fax calls to other networks.

In general, call waiting services provide an indication of a new incoming call during a telephone conversation. For an existing conversation between party A and party B, if a third caller (party C) calls party A, a tone is sent to party A. Party B is temporarily disconnected, to ensure that the tone sent to A is not also heard by party B (which would otherwise cause confusion as to whether A or B was being called by C). Party A can choose to accept the new call, by sending a "flash" signal to the exchange, or to ignore the call waiting signal.

In a duplex ringing service the line is provided with two telephone numbers which cause different ringing signals.

The different signals can be used to discriminate between voice and fax calls for example, such that calls to the fax number are automatically answered by the fax machine, while calls to the voice number are not answered by the fax machine.

In a duplex voice/fax service the normal call waiting features will cause corruption of the fax signal either because of the superimposed call waiting tone or because of the temporary disconnection of "B". In accordance with embodiments of the invention a call waiting service is provided for voice calls while suppressing the call waiting service during fax calls.

Suppression of call waiting on fax calls requires a cancel call waiting service which responds for any line whenever an incoming call has an identified telephone number allocated to fax. The local telephone exchange database is allocated a fax marker for this number, and call waiting is suppressed whenever this number called. For calls to the "voice" number on the duplex line, the call waiting service operates normally.

For outgoing fax calls, the call waiting service is suppressed by a dialled prefix before the destination number. However this requires user training and so it is normally preferable to deal with this in another way. The fax marker of the destination number is transmitted from the destination exchange to the originating exchange, allowing automatic call waiting suppression on the calling line during a fax call.

The use of database marker for fax is not widespread, so that outgoing calls to other networks without fax markers could not have automatic call waiting suppression. In this case, call waiting can be suppressed on all outgoing calls (voice or fax) to other networks. This has the benefit anyway that calls to overseas networks on IDD are not interrupted by call waiting tones from local callers.

In Figure 1, the flow chart for the network exchange programme is shown for incoming fax calls. A cancel call waiting service signal is generated to cancel or suppress the call waiting service if the called telephone number has a fax marker. In other words, any number with a fax marker, (that is. a number pre-allocated to receive fax transmissions) is recorded at the exchange as a "fax number". Whenever a fax number is called, a cancel call waiting service is automatically initiated.

In Figure 2A. when a call is made on a number that is provided with a cancel call waiting service, the caller dials an access code to cancel any cancel call waiting service the called number may have. The access code is an indication to the called number that a fax transmission is coming. The presumption is that if the caller's number is associated with a cancelling service, it must be a "fax number".

The arrangement of Figure 2A normally requires the user, that is, the caller, to apply the access code and so the arrangement in Figure 2B is preferred which is automatic.

The called number provides an indication back to the caller that a fax number has been called and on the basis of this identification the call waiting service of the caller is automatically cancelled by the exchange.

In Figure 3A when fax calls are made to other networks, the same programme can be used as for local calls so Figure 3A is the same as Figure 2A. However, as mentioned earlier, the flow chart of Figure 3A is only useful if the other network have or use suitable fax markers. It is preferably therefore to use the arrangement of Figure 3B where a cancel call waiting service is initiated if the leading digits of the called number is a fixed or certain set of digits. Such fixed set of digits are for example 001 or 011 as used for particular International calls.

This means that the call waiting service is then cancelled for all International calls, both fax (or data) and voice.

Whereas duplex lines have been described, it will be appreciated that the same arrangements can be made for multiplex lines having three or more numbers per line.

The call waiting is then cancelled or suppressed for that line if any of the lines has a fax marker or if the incoming call has been identified as a fax transmission in the manners described above.

Claims (6)

1. A multiplex telephone network having a call-waiting service for one or more lines in which some of the numbers allocated to such lines are for receiving fax transmissions. including a cancel call-waiting service that responds to transmission of facsimile data to inhibit application of a call waiting service to the line during fax transmissions.

2. A network according to claim 1. in which the cancel call-waiting service is initiated by any incoming signal to any numbers of each line that has been pre-allocated for receiving fax transmissions.

3. A network according to claim 1. in which the network is arranged to provide signals to identify to the caller that the called number has a fax marker and the cancel call waiting service responds to receipt of such identifying signals for the called number.

4. A network according to claim 1. in which the cancel call waiting service for the called line is automatically initiated when calls are made from a caller that has a cancel call waiting service.

5. A network according to claim 1 in which the cancel call waiting service is initiated whenever the leading digits of the called number have a certain fixed pattern.

6. Telephone networks substantially as herein described with reference to the accompanying drawings.