GB2346505A

GB2346505A - Supressing telephone ringing associated with predetermined CLI numbers

Info

Publication number: GB2346505A
Application number: GB0014265A
Authority: GB
Inventors: Robin Coates
Original assignee: Inventec Malaysia Corp UK Ltd
Current assignee: Inventec Malaysia Corp UK Ltd
Priority date: 1999-07-10
Filing date: 2000-06-13
Publication date: 2000-08-09
Anticipated expiration: 2020-06-13
Also published as: GB2347048A; GB0014265D0; GB2346505B; GB0014261D0; GB2347048B

Abstract

A method and apparatus for selectively suppressing the audible ring of user telephony apparatus coupled to a user telephone line of a PSTN, includes comparing calling line identity (CLI) of an incoming call with at least one stored CLI, and suppressing the ringing circuit of the telephone line if there is a match. A ring suppression circuit is employed comprising a low impedance (R1) in series with a switch (S1) to divert the ringing signal away from audible output elements such as a bell (320).

Description

METHOD AND APPARATUS FOR SUPRESSING TELEPHONE RINGING The present invention relates in general to the field of telephone apparatus, and in particular but not exclusively to a method and apparatus for selectively suppressing the audible ringing of user telephony apparatus coupled to a user telephone line of a PSTN.

Preferred embodiments of the method and apparatus are particularly suitable for use in the field of computer apparatus communicating by telephony.

In modern PSTN systems (or equivalent) call related information is provided as part of the process of establishing a call connection. The call related information may include, amongst other things, called directory number (CDN) giving the number called by the calling party, and calling line identity (CLI) information identifying the calling party. The CLI information typically includes the telephone number and area code of the calling party, and optionally includes other information such as name information associated with the calling party. In some countries, such as the United Kingdom, the PSTN supplies call related information prior to sending the first ring signal in the call connection sequence. In other countries, such as the United States, call related information is supplied between the first and second ring signals. Other call connection sequences are also known.

It is common for a single exchange line of a PSTN to be used for a number of different functions. For example, the line may be used to make and receive voice calls, fax calls, and other computer related telephony such as connection to the internet via an internet service provider (ISP). Several different user apparatus may be employed and typically each piece of user apparatus is designed to operate independently, coupled in parallel to the telephone line.

More recently, it is known to combine different functions in a single apparatus. For example, a combined voice telephone and fax apparatus is well known. Another combined apparatus is an e-mail telephone which combines the functions of a data message system with a normal voice telephone system. Typically, the data message system connects with an ISP (or equivalent) to send and receive e-mail format messages, comprising text and ideally text and graphics.

A problem has been identified in that incoming calls to a user apparatus coupled to a PSTN or equivalent will include a ringing signal, and therefore any apparatus coupled to the telephone line will ring in response to the incoming call. Further, since the user apparatus are coupled in parallel to the telephone line, each of them receives the ringing signal in common and will ring in response thereto even if the incoming call is appropriate to only one of the apparatus. For example, where the incoming call is intended to perform a data messaging function such as, for example, a fax call or a call to deliver text messages, it is desired to process the incoming call without causing any of the user apparatus to ring.

An aim of the invention to address the problems of the prior art described above, or otherwise. One aim of the present invention is to provide a method and apparatus capable of identifying incoming calls and selectively causing user apparatus coupled to the telephone line not to ring. It is an aim of a preferred embodiment of the invention to provide a method and apparatus which minimises disturbance for the user, is simple to construct and use, and is cost effective in implementation.

According to a first aspect of the present invention there is provided a method comprising the steps of receiving an incoming call, including calling line identity (CLI) information ; comparing the incoming CLI with at least one predetermined CLI ; and if the comparing step produces a match then suppressing a ringing circuit, else allowing the ringing circuit to operate.

Preferably, the method is for use with a user apparatus couplable to a user telephone line of a telephone network such as a PSTN or equivalent. The incoming CLI is provided from the PSTN, which also applies a ringing signal to the ringing circuit as part of a call connection sequence for an incoming call. Where at least one user apparatus is coupled to the user telephone line such that the incoming ringing signal is commonly received by the or each user apparatus, the PSTN applies the ringing signal until the or any one of the user apparatus answers the incoming call to continue the call connection sequence.

Also according to the present invention there is provided an apparatus comprising : receiving means couplable to a telephone line to receive an incoming call and for decoding calling line identity information supplied with the call ; comparing means for comparing the decoded calling line identity information with at least one predetermined calling line identity ; and ring suppression means for suppressing a ringing circuit on the telephone line, the ring suppression means being responsive to the comparing means.

Advantageously, in the preferred method and apparatus, when the calling line identity (CLI) of the incoming call matches a predetermined CLI, the ringing circuit is suppressed such that user apparatus coupled to the circuit does not ring. Thus, an incoming call from a predetermined calling party is recognised and the ringing circuit is suppressed such that the user is not disturbed by the incoming call. If desired, the incoming call may then be answered and dealt with as appropriate by a user apparatus. For example, an incoming fax call can be answered and a fax transmission received. In another embodiment the incoming call may be used to deliver text messages such as email or SMS.

Preferably, the ringing circuit is selectively suppressed in response to commands generated within a user apparatus and/or commands from a user. For example, the ringing circuit may be selectively disabled by the user.

Preferably, the method and apparatus allow receipt of the incoming call even if the telephone line is in use when the incoming call is received. For example, the incoming call may be received from a telephone network supporting call waiting type features (also known as caller display type 2). Optionally, ring suppression is selectively not implemented. For example, where the line is already in use ring suppression may not be appropriate.

Preferably, information identifying a predetermined calling party is stored in a memory of the user apparatus.

Preferably, the predetermined CLI information is selected at the time of manufacture or installation of the user apparatus. Preferably, the one or more predetermined CLI information are entered by the user. Preferably, the predetermined CLI information is downloaded from a remote source to the user apparatus via a telephone line.

The ring suppression circuit is suitably coupled across the ringing circuit of a telephone line, in parallel with audible output elements such as a loud speaker circuit tone caller or bell of this or other pieces of user apparatus. The ring suppression circuit preferably comprises a switch and a low impedance. In use, the switch is driven to couple the low impedance across the ringing circuit, such that the audible output elements do not operate. Suitably, the switch is an electronic switch such as a photorelay or a transistor.

Preferably, the ringing circuit is suppressed in a standby state and is only released if the comparing step does not produce a match. Advantageously, this embodiment is suited for use in countries where the PSTN sends a ringing signal prior to the call related information.

Preferably, the apparatus comprises user alerting means for alerting a human user, the alerting means being responsive to the comparing means. The user may be alerted by any suitable means. For example, the user apparatus may include a visual indicator such as an LED. Preferably, where the user apparatus includes a display screen, for example where the user apparatus comprises a data message system, the user is alerted by means of a message displayed on the screen. In other embodiments the user is alerted by an audible signal.

Preferably, the user apparatus supports a plurality of users. Suitably the user alerting means is arranged to selectively alert one or more users amongst the plurality of users, preferably responsive to the comparing means.

Ideally the comparing means determines the user or the group of users to alert based on a comparison of the calling line identity information. Ideally the CLI information contains information for selecting the user or group of users. Further, the apparatus preferably stores a plurality of predetermined CLI information, each associated with a different calling party, such that appropriate action is taken in response to an incoming call from that party.

Advantageously, a call originating from a remote source is used to notify a user. In one preferred embodiment the remote source is the server of an internet service provider (or similar) and an incoming call is used to notify a user that e-mail messages are waiting delivery. In other preferred embodiments, the notifying call is used to notify the user that, for example, shopping is ready for collection, or is an automatic reminder that library books are due for return. In another group of preferred embodiments the notifying call is used to control the user apparatus or a related device.

For example, the notifying call may be used to control the user apparatus, such as to turn on or off or to implement any other suitable control parameter. Further still, the notifying call may be used to control related devices, for example to switch on a video cassette recorder or a domestic appliance such as a washing machine or a cooker. The principles of the present invention will find practical application in many different embodiments.

In the preferred embodiment concerning the delivery of e-mail messages, the method suitably further includes-the step of initiating an outgoing call from the user apparatus to the remote server to provide for the collection of waiting messages. Preferably, the user initiates the call from the user apparatus in response to the notifying call. Further preferably, the user apparatus automatically initiates the call to provide for delivery of waiting messages, in response to receiving the notifying call.

Advantageously, the notifying call from the server to the user apparatus is relatively short, for example of the order of five seconds. Thus, calling time requirements and call charges for the server are minimised. The user may arrange for collection of waiting messages at a time convenient to the user and this outgoing call, which usually takes much longer than the notifying call, is arranged and paid for by the user.

Also according to the present invention there is provided a method comprising the steps of : a) receiving an incoming call, including calling line identity (CLI) information ; b) comparing the incoming CLI with at least one predetermined CLI ; c) suppressing a ringing circuit in a standby state, and allowing the ringing circuit to operate only if the step (b) does not produce a match.

Further according to the present invention there is provided a method for use with at least one user apparatus coupled to a user telephone line of a PSTN, the method comprising the steps of : al) applying a ringing signal generated by the PSTN to the user telephone line as part of a call connection sequence of an incoming call ; a2) receiving the incoming call at the user apparatus--and decoding calling line identity (CLI) information ; b) comparing the incoming CLI with at least one predetermined CLI ; and c) if the step (b) produces a match then (cl) suppressing a ringing circuit of the user telephone line, else (c2) allowing the ringing circuit to operate in response to the ringing signal such that the call connection sequence is continued and completed.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which : Figure 1 is a schematic block diagram showing user apparatus coupled to a telephone line ; Figure 2 is a schematic block diagram showing a remote server and user apparatus coupled by a PSTN network ; Figure 3 is a schematic block diagram of a user apparatus ; Figure 4 is a schematic circuit diagram of a first preferred ring suppression circuit ; and Figure 5 is a schematic circuit diagram of a second preferred rina suppression circuit.

The preferred embodiments of the invention will be described with reference to the example of a method and apparatus for use with a public switched telephone network (PSTN). Other embodiments work with other forms of telephone network, such as a private branch exchange (PBX). Reference to a telephone line is generally intended to mean transmission along a set of physical wires, but where is context is appropriate can also include transmission by other means such as wireless transmission using radio signals, light signals or other signals.

Figure 1 shows three sets of user apparatus 31, 32 and 33 coupled to a user telephone line 30. For example, a first user apparatus 31 might be an e-mail telephone, while other apparatus (in this case the second and third apparatus 32 and 33) might be an ordinary voice telephone, an answering machine, a fax machine or a computer apparatus. In most environments, including a domestic or small office (SoHo) environment the telephone line 30 is the responsibility of the user, and is coupled to an external telephone network via a connection box 40.

Figure 2 shows a server 11 coupled via a local telephone line 10 to a telephone network such as a public switched telephone network (PSTN) 20 allowing a call to be routed through to a called number corresponding to a particular user telephone line 30 having a user apparatus 31 coupled thereto. In this example the user apparatus is an e-mail telephone. An e-mail telephone 31 is an apparatus for making and receiving normal voice calls using the telephone line 30, and also for sending and receiving data typically in the form of text messages in a format suitable for e-mail transmissions. To send and receive e-mail messages the user apparatus 31 is coupled through the PSTN 20 to the server 11 of an internet service provider or equivalent. Messages prepared off line at the e-mail telephone 31 are then transmitted to the server 11 for forwarding across data communication networks as appropriate including the PSTN 20 or otherwise. Messages intended for the user (s) of the e-mail telephone 31 are received at the server 11 and wait at the server ready for delivery to the e-mail telephone 31 (or other apparatus) at the request of the user across the PSTN 20. The user apparatus 31 initiates a call to the server 11 in order to send and receive e-mail messages.

Normally, the user apparatus 31 must initiate a call to see if mail is waiting on the server 11 ready for delivery. If no mail is waiting then potentially this call is wasted. It is desired to provide a fast, efficient and simple method of notifying the user apparatus 31 that a message is waiting on the server 11 ready for delivery.

In the preferred embodiment, the server 11 initiates an outgoing call to the user apparatus 31 across the PSTN 20 in response to a predetermined condition. Ideally the condition is that at least one e-mail message is waiting at the server 11 for delivery to the user. However, other conditions can be used such as waiting for a predetermined number of messages or a predetermined quantity of data before initiating the outgoing call. These conditions can be set by the ISP operating the server 11, or optionally can be set by the user such as by dialling into the server 11 using the user apparatus 31. Other conditions include, for example, important announcements that the ISP wishes to transmit to all users or a selected group of users.

This may include information concerning services available on the server 11 and may include advertising information.

Further, the outgoing call may be initiated in order to update information stored on the user apparatus 31.

The notifying call initiated by the server 11 is routed by the PSTN 20 to the user's telephone line 30.

The call connection sequence includes the transmission of a ringing signal received in common by the or each user apparatus 31 coupled to the telephone line 30. In the example arrangement shown in Figure 1, the ringing signal from the PSTN is received by each of the user apparatus 31, 32 and 33 coupled to the user telephone line 30. Normally the ringing signal will continue until one piece of user apparatus 31, 32 and 33 answers the call such that the call connection sequence is continued and completed to establish the call connection with the calling party. At that point, the PSTN 20 will monitor the status of the call and record billing information. Usually, calls are charged to the calling party from the point of connection.

It is desired to provide a notifying call from one piece of apparatus such as the server 11 to another piece of apparatus such as the user apparatus 31 without requiring the call connection sequence to be completed. This keeps call time and network usage to a minimum, and economises billing by the PSTN 20 or equivalent. In the example situation described above, the PSTN 20 generates call related information including a calling line identifier information for identifying the calling party which is transmitted to the called party, in this case the user apparatus 31.

Figure 3 is a schematic block diagram of the user apparatus 31. The user apparatus includes a number recognition unit 311, a notifying unit 312, and a ring suppression unit 313. In use the number recognition unit 311 is coupled to the user telephone line 30 and receives the call related information transmitted from the PSTN 20 when trying to connect a new call.

The user apparatus includes a memory, suitably part of the number recognition unit 311, for storing one or more predetermined calling line identifiers, ideally the calling party number or name information. In use the number identifier unit 311 decodes the call related information and extracts the calling line identity (CLI) information. The CLI information is compared with the stored CLI information to determine whether the incoming caller is a recognised caller. If the incoming caller is recognised as the server 11 (or other equivalent source) then the incoming call is determined as, for example, a notifying call intended to show that e-mail messages (or similar) are waiting for delivery at the server 11. The user apparatus 31 then provides appropriate notification to the user via the user notification unit 312. In other preferred embodiments the notification unit 312 takes action automatically in response to a notifying call from a recognised caller. For example, in the preferred embodiment where the user apparatus is an e-mail telephone, the user apparatus may automatically make an outgoing call in order to provide for delivery of waiting e-mail messages. In other preferred embodiments other action may be taken as appropriate in response to the notifying call. For example, the user apparatus may arrange for that apparatus or another connected apparatus to switch on or off or be programmed as appropriate. For example, the notifying call in one embodiment might be used to turn on a video cassette recorder or a domestic appliance such as a washing machine or cooker.

The notification unit 312 may take any suitable form, depending on the nature of the user apparatus 31. For example, where the user apparatus is an e-mail telephone, the user notification unit 312 generates a message for display on a screen of the e-mail telephone indicating that new mail awaits delivery. The user apparatus 31 may support more than one user, such as different e-mail accounts within a single e-mail telephone. Suitably, the user notification unit 312 provides notification selectively to the or each user. In the preferred embodiment the number recognition unit 311 determines the user or users amongst the plurality of users to notify based on information contained in the CLI information.

For example, the CLI information may use a different calling line identity appropriate to each user.

Even though the notifying call from the server 11 is relatively short, preferably of the order of five seconds, it may be inconvenient for the user to hear the incoming call due to the ringing signal reaching other user apparatus such as the apparatus 32 or 33 of Figure 1.

Further, where such other apparatus, is, for example, an answering machine, then the call may be answered where this is not desired. Therefore, the user apparatus 31 includes a ring suppression circuit 313.

Figure 4 shows a first preferred ring suppression circuit in more detail. The ring suppression circuit 313 is coupled across the signal wires of the user telephone line 30 carrying the ringing signal, in parallel with sound output units such as a tone caller 320. The ~ring suppression circuit 313 suitably comprises a switch, ideally an electronic switch such as a transistor or a photo relay S1, in series with a low impedance such as a resistor R1. The low impedance is selected such that when the switch S1 is turned on and current flows through the low impedance R1, the majority of the current on the ringing circuit of the user telephone line 30 flows through the low impedance R1 and does not reach any audible output units such as the loud speaker 320.

On three wire telephone systems the ring suppression circuit 313 is applied directly across the ring circuit, as shown in Figure 4. Figure 5 shows a second preferred ring suppression circuit for use on two wire telephone systems applied directly across the two wire connection together with a DC block, in this example a capacitor C1, to prevent auto answering of the call.

Referring again to Figure 3, when the number recognition unit 311 recognises the identity of the calling party, the ring suppression circuit 313 is operated to suppress ringing on the user telephone line 30. Where the call related information is sent prior to the ringing signal, then suitably the ring suppression circuit 313 is engaged to suppress ringing prior to the first ringing signal if the calling party is recognised by the number identification unit 311. However, in other situations the ring suppression unit 313 is normally engaged in a standby mode such that initially ringing tone on the ring circuit of the user telephone line 30 is always suppressed. Only when the number recognition unit 311 determines that the incoming call is not from a recognised calling party is the ringing circuit released for normal operation and the call connection sequence continues. Further still, the ring suppression circuit 313 can be optionally engaged, under the control of the user apparatus 31 or under control of the user.

According to another preferred embodiment of the present invention, it is desired to provide a convenient method for delivery of data messages and in particular short message service (SMS) type data packets from a remote server to the user apparatus. Here, it is desirable that the user apparatus receives the incoming call and recognises the CLI as described above. If the incoming call is determined as coming from an SMS message server, the call is answered (with ring suppression if desired) to enable data packets to be delivered from the SMS server to the user apparatus. Here, the SMS server makes an outgoing call which is received by the user apparatus and a call connection sequence is desirably completed. However, the SMS data packet is relatively short with messages typically having a free text user data field of only 160 characters, such that the delivery call is of relatively short duration.

In each of the preferred embodiments, an incoming call may be received and processed by the user apparatus 31 even when the user telephone line 30 is in use. Ideally, the telephone network 20 supports a call waiting feature such that a second (or further) call can be supplied to the user telephone line 30. Ideally the user apparatus 31 determines whether the telephone line 20 is already in use, and if so then applies CLI recognition to determine whether the new incoming call is from a recognised caller and determines whether ring suppression is required.

A method and apparatus has been described which, advantageously, enables a notification message to be delivered from one piece of apparatus to another, such as from a server of an ISP to a user, ideally to an e-mail telephone. The notifying call is quick, efficient and cost effective. A method and apparatus has also been described enabling delivery of a data message. Further, the method and apparatus described above advantageously allow the notifying call or message delivery call to be received without disturbing the user by suppressing the ringing circuit.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s). The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS 1. A method comprising the steps of : a) receiving an incoming call, including calling line identity (CLI) information ; b) comparing the incoming CLI with at least one predetermined CLI ;

c) if the step (b) produces a match then- (cl) suppressing a ringing circuit, else (c2) allowing the ringing circuit to operate.
2. A method as claimed in claim 1 wherein, in the step (a), the incoming call is received on a user telephone line.
3. A method as claimed in claim 2 wherein, in the step (a), the user telephone line is coupled to a PSTN.
4. A method as claimed in claim 3 wherein, in the step (a), the incoming CLI is provided from the PSTN.
5. A method as claimed in any of claims 1 to 4, wherein the step (a) comprises applying an incoming ringing signal.
6. A method as claimed in claim 5, wherein the step (c) comprises providing the ringing circuit for receiving the incoming ringing signal.
7. A method as claimed in claim 6, wherein in the step (c), the ringing circuit includes at least one user apparatus such that the incoming ringing signal is received by the or each user apparatus.
8. A method as claimed in any of claims 5 to 7, wherein the step (a) comprises applying the ringing signal until the or any one of the user apparatus answers the incoming call to continue a call connection sequence.
9. A method as claimed in any of claims 1 tu--8, wherein the step (c) comprises selectively coupling a ring suppression circuit in parallel with the ringing circuit.
10. A method as claimed in any of claims 1 to 9, wherein the step (c) comprises coupling a ring suppression circuit across two signal wires of the ringing circuit carrying a ringing signal.
11. A method as claimed in claim 10, wherein in the step (c), the ring suppression circuit comprises an impedance provided between the two signal wires such that a majority of current on the ringing circuit flows through the impedance
12. A method as claimed in any of claims 1 to 11, wherein in the step (c), the ringing circuit includes at least one audible output element for generating a user audible ring.
13. A method as claimed in claim 12, wherein the ring suppression circuit is provided such that substantially no current reaches the or each audible output element.
14. A method as claimed in any of claims 1 to 13, wherein the step (c) comprises selectively suppressing the ringing circuit in response to commands generated within a user apparatus and/or commands from a user.
15. A method as claimed in any of claims 1 to 14, wherein the step (c) comprises selectively suppressing the ringing circuit only if the telephone line is not already in use when the incoming call is received.
16. A method as claimed in any of claims 1 to 15, wherein the step (cl) comprises suppressing the ringing circuit in a standby state, and the step (c2) comprises releasing the ringing circuit if the step (b) does not produce a match.
17. A method as claimed in any of claims 1 to 16, wherein the step (cl) comprises the steps of (cll) suppressing the ringing circuit and (cl2) answering the incoming call while the ringing circuit is suppressed to complete a call connection sequence.
18. A method as claimed in claim 17, wherein the step (cl2) includes allowing the delivery of a data message from a remote server coupled to the PSTN.
19. A method as claimed any of claims 1 to 18, wherein the step (c) includes recording that a match has occurred.
20. A method as claimed in any of claims 1 to 19, wherein the step (c) includes alerting a user that a match has occurred.
21. A method comprising the steps of : a) receiving an incoming call, including calling line identity (CLI) information ; b) comparing the incoming CLI with at least one predetermined CLI ;

c) suppressing a ringing circuit in a standby state, and allowing the ringing circuit to operate only^if the step (b) does not produce a match.
22. A method for use with at least one user apparatus coupled to a user telephone line of a PSTN, the method comprising the steps of : al) applying a ringing signal generated by the PSTN to the user telephone line as part of a call connection sequence of an incoming call ; a2) receiving the incoming call at the user apparatus and decoding calling line identity (CLI) information ; b) comparing the incoming CLI with at least one predetermined CLI ; and

c) if the step (b) produces a match then (cl) suppressing a ringing circuit of the user telephone line, else (c2) allowing the ringing circuit to operate in response to the ringing signal such that the call connection sequence is continued and completed.
23. An apparatus comprising : receiving means couplable to a telephone line to receive an incoming call and for decoding calling line identity information supplied with the incoming call ; comparing means for comparing the decoded calling line identity information with at least one predetermined calling line identity ; and ring suppression means for selectively suppressing a ringing circuit of the telephone line, the ring suppression means being responsive to the comparing means.
24. An apparatus as claimed in claim 23, wherein the ring suppression means is arranged to suppress an incoming ringing signal applied to the ringing circuit of the user telephone line.
25. An apparatus as claimed in claim 23 or 24, wherein the ring suppression means is coupled in parallel with the ringing circuit.
26. An apparatus as claimed in any of claims 23 to 25, wherein the ring suppression means is coupled across two signal wires of the user telephone line that carry a ringing signal and form part of the ringing circuit.
27. An apparatus as claimed in any of claims 23 to 26, wherein the ring suppression means is couplable across the ringing circuit of the telephone line, in parallel with audible output elements such as a loud speaker circuit tone caller or bell of this or other pieces of user apparatus.
28. An apparatus as claimed in any of claims 23 to 27, wherein the ring suppression means comprises an impedance provided between the two signal wires such that a majority of current on the ringing circuit flows through the impedance.
29. An apparatus as claimed in any of claims 23 to 28, wherein the ring suppression means is coupled to"the ringing circuit that includes at least one audible output element for generating a user audible ring in response to the ringing signal, and wherein the impedance of the ring suppression means is provided such that, in use, substantially no current reaches the or each audible output element.
30. An apparatus as claimed in any of claims 23 to 29, wherein the ring suppression means comprises a switch for selectively engaging the ring suppression means.
31. An apparatus as claimed in claim 30, wherein the switch is arranged in series with the impedance.
32. An apparatus as claimed in claim 30 or 31, wherein the switch is operable in response to commands from a user.
33. An apparatus as claimed in any of claims 30 to 32, wherein the switch is responsive to commands generated within the user apparatus to selectively enable the ring suppression means.
34. An apparatus as claimed in any of claims 23 to 33, comprising means for determining whether the telephone line is already in use when the incoming call is received, the ring suppression means being responsive to the determining means such that the ring suppression means is selectively not engaged if the telephone line is already in use.
35. An apparatus as claimed in any of claims 23 to 34, wherein the ring suppression means is arranged to suppress the ringing circuit in a standby state, and to selectively release the ringing circuit.
36. An apparatus as claimed in any of claims 23 to 35, wherein the receiving means is arranged to selectively answer the incoming call in order to complete a call connection sequence.
37. An apparatus as claimed in any of claims 23 to 36, wherein the receiving means is arranged to answer the incoming call while the ringing circuit is suppressed by the ring suppression means.
38. An apparatus as claimed in any of claims 23 to 37, wherein the comparing means comprises a memory for storing a plurality of predetermined calling line identity (CLI) information, each for identifying a different calling party.
39. An apparatus as claimed in any of claims 23 to 38, wherein the comparing means is arranged to store CLI information selected at the time of manufacture or installation of the user apparatus, or entered by a user, or downloadable from a remote source to the apparatus via the telephone line.
40. An apparatus as claimed in any of claims 23 to 39, further comprising means for alerting a user that a match has occurred, in response to the comparing means.
41. An apparatus as claimed in any of claims 23 to 40, wherein the apparatus is couplable to a user telephone line of a PSTN.
42. An apparatus as claimed in claim 41, wherein the PSTN is arranged to generate the calling line identity information of the incoming call.
43. A method substantially as hereinbefore described.
44. A method as claimed in claim 1 and substantially as hereinbefore described.
45. A method as claimed in claim 21 and substantially as hereinbefore described.
46. A method as claimed in claim 22 and substantially as hereinbefore described.
47. An apparatus substantially as hereinbefore described.
48. An apparatus substantially as hereinbefore described with reference to Figures 3, 4 and 5 of the accompanying drawings.