GB2202410A

GB2202410A - Automatic dialling device

Info

Publication number: GB2202410A
Application number: GB08701989A
Authority: GB
Inventors: David Thomas Venn
Original assignee: Mercury Communications Ltd
Current assignee: Mercury Communications Ltd
Priority date: 1987-01-29
Filing date: 1987-01-29
Publication date: 1988-09-21
Anticipated expiration: 2007-01-29
Also published as: GB8701989D0; GB2202410B

Abstract

An automatic dialing device for use with a telecommunications network comprises an input port for connection to the telecommunications apparatus 5 of a first user, an output port for connection to the telecommunications network PSTN, and means for maintaining a continuous conductive connection between the input port and output port in a passive state of the device. On detection of a specific string of dialled digits on the input port the continuous conductive connection between the input port and the output port is broken and successive signals received on the input port are stored. A signal is then produced, by control circuitry 2 including a microprocessor 15, on the output port to cause connection to a second telecommunications network, connected to the first telecommunications network. Subsequent signals on the input port are passed to the output port. <IMAGE>

Description

AUTOMATIC DIALLING DEVICE This invention relates to an automatic dialling device for use with a telecommunications network, and in particular for a device intended to be interposed between telecommunication apparatus of a user, and the telecommunications network.

A wide range of types of auto dialling equipment is currently is use worldwide on the various public switched telephone networks (PSTN's).

When a single telecommunications network is available to a user, all that is necessary of the user's equipment is that it should be able to carry to the network the code required for the subscriber to which connection is desired. In circumstances where two or more telecommunications networks are available however, it will often be necessary for the equipment of a user to select which of the networks it is to utilise for making any given connection, particularly when it is possible to connect to the other subscriber by two or more alternative networks. For reasons of economy, the telecommunications lines of a particular user will in general be operated by a single network, and the usual mechanism for obtaining connection via the network of another operator is to dial the access number of the other operator, via the first operator's network.

The second network will then generally require certain identifying signals to be passed to it, for example a string of digits, to identify the user, followed by further identifying signals, to identify the subscriber which the user wishes to contact.

Additionally, the second network operator may require certain other identifying signals to be provided, for example a "personal identification numberu (PIN).

Thus, the user, to obtain a connection to a subscriber via the second network, may be required to generate a long sequence of signals or digits. For this reason, the procedure is not only prone to error, but can also result in a long delay in the connection to the second subscriber being established.

Various auto dialling devices are available which can minimise some of the above difficulties, but devices proposed to date do not enable the use of the full facilities of a second telecommunications network, whilst requiring minimum user intervention, and whilst not interfering with ordinary call making to the primary telephone network, in the event of power failure or equipment failure, or should a user wish to route a call via his primary network, According to a first aspect of the invention, there is provided an automatic dialling device for use with a telecommunications network, comprising:: an input port for connection to the telecommunications apparatus of a first user, an output port for connection to the telecommunications network, means for maintaining a continuous conductive connection between the input port and the output port in a passive state of the device, for example when the device is quiescent, faulty, or has suffered a power failure, means for detecting the occurrence of a specific input signal on the input port, for example a dialled digit indicating that the first user wishes to make a long-distance call, and for breaking the continuous conductive connection between the input port and the output port and storing successive signals received on the input port, on occurrence of the said specific input signal, means for producing automatically a signal on the output port adapted to cause connection to a second telecommunications network, means for causing subsequent signals on the input port to be passed to the output port, means for detecting a call termination signal of a call routed through the device, and means for ensuring restoration of the said continuous conductive connection, on detection of the said a call termination signal.

Preferably, the device in accordance with the invention is utilised for enabling a connection via the second network, to a subscriber who can be reached by either the first or second networks. Thus, the specific input signal which generates the breaking of the continuous conductive connection may be a dialled digit, indicating that the user wishes to establish a long-distance connection (for example a zero). The device may then cause comparison of the said stored successive signals, indicative of the area code of the subscriber it is desired to contact, with at least one stored reference signal indicative, for example, of areas which may be contacted via the second network.

Means responsive to the said comparison means are then provided for disabling the automatic signal producing means, and for causing the said stored successive signals to be transferred to the output port, in dependence upon the results of the said comparison.

For example, if the second network is capable of connection only with locations having certain area codes, the digits representing the area code are stored, and compared by the device with pre-programmed digit sequences, representing the area codes accessible by the second network. If the dialled sequence of digits agrees with one of the stored reference sequences, then the device outputs on the output port a signal, for example a sequence of digits, which cause connection through the first telecommunications network to the second, followed by the sequence of signals recognized by the second network as representing the corresponding area.If the area code is not recognized by the device as one accessible on the second telecommunications network, then the said stored successive signals are output directly to the output, so that connection can be established via the first telecommunications network.

After the area code digits have been output, the conductive connection between the input and output ports may be re-established, and the device may return to its idle state.

The means for causing subsequent signals on the input port to be passed to the output port, after connection to the second network, may, if desired after the form of signalling, for example from pulse signalling to multifrequency signalling, or.vice versa.

Means may preferably be provided for enabling the said stored reference signals to be changed by a user of the device, so that, as the second telecommunications network becomes able to deal with an increasing number of subscriber areas, an increasing number of call may be routed to the second telecommunications network. The reference signals may preferably be stored in look-up tables, held in non-volatile electronic memory. Such look-up tables may have capacity for, for example, three hundred three digit codes, for storing national area codes, and four hundred four digit, and fifteen seven digit codes, for storing international area codes.

The device in accordance with the invention preferably includes means for overriding the automatic route selection, by recognizing a sequence of signals from the input port, and providing preferential routing of a call, in response thereto, via the primary telecommunications network or the secondary network.

In a preferred embodiment, means are provided within the device for detecting when the second telecommunications network is unable to effect the desired subscriber connection, and for releasing and reseizing the telecommunications link with the primary telecommunications network in such circumstances, whereby the call may be re-routed wholly by the first telecommunications network. Thus, the signals or dialled digits associated with the desired call may be stored in the device, and retransmitted to the primary telecommunications network, when the link has been re-established. This sequence may be initiated, for example, by a "timeout" facility, when the second network fails to provide the desired connection within a predetermined time, or by the receipt of a predetermined tone (a "splash back" tone) from the second network. Such a "splash back" tone may be generated by the second network when for some reason it is unable to provide the desired link.

On connection to the second network, the device in accordance with the invention may generate a sequence of identification signals or digits, to identify the second user, for example to identify the account number of the user and/or a personal identification number to enable the user to prevent unauthorised use of his account.

Detection of the termination of the call may be carried out, for example, by detection of a "loop" condition.

A preferred embodiment of the invention is described with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of apparatus in accordance with the invention, and Figure 2 is a flow diagram governing the operation of apparatus as shown in Figure 1.

Dealing first with Figure 1, an automatic dialling device comprises a back plane 1, into which is removeably connected a control card 2, and at least one line card 3. The device also incorporates a switching device 4, connected, in the case illustrated, to the public switched telephone network (PSTN), and to five telephone instruments 5 (one only shown, for clarity). The switching unit 4 is such that, in the quiescent state of the unit, the five telephone instruments are connected directly, via a metallic path, to five lines of the PSTN. That metallic path can however be interrupted, under the control of the control card 2, and data may be from the control card sent to the PSTN.

Line card 3 carries five circuits, 6, 7, 8, 9 and 10, each associated with one of the telephone instruments. Circuits 6 to 10 monitor the lines connected to telephones 5, and detect dialled digits, either loop disconnect (LD) or multi frequency (MF).

When a dialled digit is detected by the respective circuit 6 to 10, a status indicator is set.

Control card 2 comprises a microprocessor 15, key pad 16, and four digit LCD display 17. The card also comprises 2K of non-volatile RAM (NVRAM) 18, and a power supply unit 19. A programme for the microprocessor 15 is also provided, stored in a further block 21 of NVRAM. The microprocessor 15, under the control of the programme in EPROM 21 polls circuits 6, 7, 8, 9 and 10 successively, to test whether the corresponding telephone 5 has dialled a digit. The microprocessor 15 may then, depending upon the program, send an appropriate signal via the back plane 1 to the switching device 4, to interrupt the connection between the corresponding telephone 5 and PSTN, store digits from the telephone 5, and forward those digits later, if desired with other code digits interposed, to the PSTN.

Each circuit 6 to 10, when polled, returns a signal to the microprocessor 15 to indicate that that circuit is "temporarily idle" (i.e. the corresponding telephone 5 has not provided a dialled digit). If, within a pre-set period, for example half a second, the "temporarily idle" signal is not received, the microprocessor 15 flags the corresponding circuit (e.g. 6 as out of service. In the event that a dialled digit is received, the digit is forwarded to the microprocessor 15, before the microprocessor moves on to poll the next circuit.

A plurality of line cards 3 may be provided, so as to provide, say, forty circuits, utilising eight line cards 3. A single control card 2 may be utilised to control up to forty circuits.

The control card 2 is also provided with a connection 30 to a security switch, to enable the automatic system to be overridden.

The apparatus shown in Figure 1 may operate in one of two modes, designated herein as "mode A" and "mode B".

Mode A In this mode, a key-operated security switch, connected to point 30 on control card 2, is operated, and at all times, calls will be routed to the primary network. Operation of the key operated security switch causes the key pad 16 to be enabled, so that the microprocessor 15 responds to signals therefrom.

In addition, the four digit LCD unit 17 is activated, and displays a "?". This indicates to the user that the key pad is activated. In this mode, if a number is dialled by a user, the direct metallic connection between telephone 5 and PSTN is split, but calls are always routed via the primary network or PSTN. The key pad may be operated to instruct the microprocessor 15 to store in NVRAM 18 various codes, for example area codes to which the device will respond, personal identification numbers (PIN's) customer account numbers, and. the like. Means may also be provided for outputting, either to the LCD unit 17, or to an alternative display unit, the various codes stored in NV RAM 18. After the desired codes have been entered in this mode, the security device may be returned to its original position.In this position, the LED unit 17 displays the word "poll", to indicate that the microprocessor 15 is active in polling circuits six to ten.

Mode B - Active Mode This is the normal mode of operation of the device. For operation in this mode, the LCD display device 17 must be in the state in which it displays the word "poll".

As indicated above, as soon as a digit is dialled by the telephone 5, the commencement of dialling is detected by the appropriate one of circuits 6 to 10, and the direct metallic path between telephone 5 and the PSTN is interrupted. If, for example, in Figure 1 a digit is received by circuit 6, the corresponding status flag associated with circuit 6 is set, so that the detection of a digit can be detected by the microprocessor 15 on the next polling cycle.

Subsequent digits are intercepted by circuit 6, and passed to microprocessor 15.

Microprocessor 15 compares the initial string of digits with a string of long distance codes held in NVRAM 18. If no match is found, the digits stored so far are output to the PSTN line, and the direct metallic path is then restored.

If the microprocessor 15 detects that the initial string of digits detected from circuit 6 represents an area code which is stored in NVRAM 18, this signifies that the desired call can be routed through an alternative telephone network. In this case, when the match has been found, a sequence of digits is output on the PSTN line which will cause connection through the PSTN to a local node of the second telephone network. After outputting the digits, the control processor monitors the PSTN line for detection of the dialling tone for the second telephone network. When this dialling tone has been detected, digits are output, preferable using MF signalling, to indicate to the second network the identity of the caller (a PIN) and, if desired, any other sequence of authorisation codes. The stored digits from telephone~5 are then passed by the microprocessor 15 to the PSTN line, and thus to the second telephone network. When the dialling process has been completed, the metallic path between the telephone and the PSTN is restored, to enable the call to take place.

Termination of the call is detected by any desired means, and thereafter the apparatus extends the appropriate signal to the PSTN to indicate clearing of the call.

If, for any reason, connection cannot be achieved via the second network, the initial call may be terminated, and the further call initiated through the PSTN, utilising the digits originally input at the telephone.

In additional to the codes stored in NV RAM 18 corresponding to long distance codes accessible to the second network, two special codes are stored, for example "121" and "131", which when used to prefix a dialled number, force the system to attempt to route the call either through the PSTN (121) or the second network (131). Figure 2 illustrates the above process in more detail, by means of a flow chart. -- It will of course be appreciated a wide range of alternative arrangements are possible, within the scope of the present invention.

In a further preferred embodiment, not only may the apparatus include means for comparing a personal identity code (PIN) input by a user with a stored value, and for connecting the call only if the code and valve match, in order to prevent unauthorised use, also the apparatus may include means for altering, for example incrementing, the stored value, on each use of the respective personal identity code, to provide additional security against fraudulent use.

Claims

1. An automatic dialling device for use with a telecommunications network, comprising an input port for connection to the telecommunications apparatus of a first user an output port for connection to the telecommunications network, means for maintaining a continuous conductive connection between the input port and output port in a passive state of the device, means for detecting the occurrence of a specific input signal on the input port, and on occurrence of the said specific input signal breaking the continuous conductive connection between the input port and the output port and storing successive signals received on the input port, means for producing automatically a signal on the output port adapted to cause connection to a second telecommunications network, connected to the first telecommunications network, means for causing subsequent signals on the input port to be passed to the output port, means for detecting the termination of a call, and means for ensuring restoration of the said continuous conductive connection and detection of a call termination.

2. Apparatus as claimed in claim 1, including means -for causing a comparison of the said stored successive signals with at least one stored reference signal, means responsive to the said comparison means for disabling the said automatic signal producing means, and causing the said stored successive signals to be transferred to the ouput port, in dependence upon the result of the said comparison.

3. Apparatus as claimed in claim 2, including means for restoring the said continuous conductive connection between the input port and the output port, following transfer of the said stored signals to the output port.

4. Apparatus as claimed in claim 2 or claim 3, including means for enabling the said stored reference signals to be changed by a user of the device.

5. Apparatus as claimed in any one of claims 2 to 4, wherein the stored reference signals are multi-digit codes.

6. Apparatus as claimed in any one of the preceeding claims, including means for releasing and reseizing a communications link with a telecommunications network, on detection by the device of a predetermined condition following connection to the second telecommunications network.

7. Apparatus as claimed in claim 6, wherein the predetermined condition is the receipt by the device from the second telecommunications network of a predetermined signal.

8. Apparatus as claimed in any one of the preceeding claims, including means for producing a sequence of identification signals, to identify the said first user, on connection to the said second telecommunications network.

9. Apparatus as claimed in any one of the preceeding claims, including means for comparing a personal identity code input by a user with a stored value.

10. Apparatus as claimed in Claim 9, including means for altering automatically the stored value, on each occasion that the respective personal identity code is utilised.