A TELEPHONE

Abstract: A telephone is provided with dialling means (120) to output a dialled number signal and a route determining means (121, 127) for determining an access code to route the telephone call via a preferred route provided by a service provider. A keypad (122) of the telephone is provided with a key (128) for generating a user intervention to prevent automatic operation of the route determining means to insert an access code so that, in normal use, the user is required only to input the call destination telephone number to achieve optimum routing. The user however has the option of intervening to prevent automatic call routing by actuating a function key of the telephone keypad. Calls routed to a service provider may be authenticated using an authentication procedure in which an authentication data signal is transmitted to the telephone which encrypts the data using an encryption key before returning the encrypted authentication data signal. The telephone is suitable for domestic and business use to provide optimum routing with minimum operator input and automatic authentication without use of PIN numbers.

Description: A TELEPHONE The present invention relates to a telephone and a related method of using a telephone. Primarily, but not exclusively, the present invention is concerned with telephones which are connected via signal lines to a Public Switched Telephone Network. In recent years many countries have liberalised their telecommunication systems. As a result, when a user operates a telephone, the user increasingly has a choice as to the telecommunication service provider who will connect the user to the desired call destination. The main service provided by the service providers is routing calls from the originating telephone to the destination telephone. In addition, however, other auxiliary services may be provided such as, in the case where the user at the destination telephone is not there to answer the call, storing a message from the user of the originating telephone which may subsequently be accessed by the user at the destination telephone. A system is known in which a user, when desiring to make a call, can first telephone a service provider by manually inputting the call number of that service provider. Alternative systems require the user to simply press an access selection function button of the telephone, in response to which the telephone automatically generates the call number of the service provider, and the user is then able to subsequently dial the destination number required so that the service provider determines onward routing of the telephone call . The service provider utilises a call line identifier signal generated by the local exchange through which the user's telephone call is directed to the service provider in order to automatically generate billing information. It is also known to provide routing modules connected in line with a telephone so that the output line from the telephone is input to the routing module, the output of the routing module then being connected to the public service telephone network. Such routing modules intercept dialled numbers for outgoing calls from the telephone and, depending upon the initial digits detected in the outgoing call, determine whether the call is a long distance call which could be more economically routed via a service provider. The routing module then automatically inserts an access code before transmitting the user dialled call number. Such routing modules are essentially transparent to the user who will have no control over the routing decision taken by the module. There therefore exists a need for providing an improved telephone which is simple to use but which retains flexibility and user control over the routing of telephone calls. A further aspect of the invention relates to authentication of the origin of a user request for services from a service provider. When the user is connected to the service provider, the service provider may in some instances prompt the user to send a personal identification number (PIN) which identifies the user to the service provider for the purpose of charging for services provided. Once the service provider has identified the user, a dial tone is presented to the user prompting the user to enter the call number of the desired destination. Such reliance upon PIN is convenient for users who wish to make calls from many different locations. A problem exists however where a user makes frequent calls from a single terminal in that the repeated use of PIN becomes tiresome. A PIN may also be forgotten by a user. A PIN may also become known to a third party who may make fraudulent use of the PIN, the PIN system of authentication thereby providing only a limited level of security. A further problem experienced by service providers is that, where billing information is derived from a Call Line Identifier (CLI) signal generated by a local exchange to identify the location from which a call originates, fraudulent use is possible by forging the CLI signal. The present invention seeks is to provide an improved telephone and method of making calls via a node associated with a service provider. According to the present invention there is disclosed a telephone comprising; dialling means operable to output a dialled number in the form of a signal representative of a destination of a telephone call; control means operable to control operation of the dialling means; a keypad responsive to user actuation to input a user generated call number to the control means; route determining means selectively operable to determine an access code for routing the telephone call via a preferred route; the keypad comprising a user intervention means responsive to user actuation to signal to the control means a user intervention condition; wherein the control means is operable in the absence of said user intervention condition being signalled to control the dialling means to output a dialled number including the access code determined by said route determining means followed by the user generated call number; and wherein the control means is operable in response to said user intervention condition being signalled to control the dialling means to output a dialled number comprising only the user generated call number. The telephone of a preferred embodiment has the advantage that it is no longer necessary for a user to remember every time a call is made to first dial the access number of the service provider to press an access selection key. The telephone of the present invention is suitable for both home and work environments. In the preferred embodiment, the preferred route corresponding to the access code results in the telephone call being directed to a predetermined node of a telephone network, the telephone further comprises authenticating means operable to receive an authentication data signal from the predetermined node and to automatically generate and transmit an authentication response signal to the predetermined node to confirm the identity of the communication terminal to the predetermined node. The preferred embodiment has the advantage that a user is not required to memorize a personal identification number. In the preferred embodiment, the telephone may further comprise means for encrypting the received authentication data signal using a predetermined encryption procedure and an encryption key identifying the telephone in order to form the authentication response signal . The use of encryption thereby improves security by providing an encrypted "handshake" procedure between the callers telephone and the predetermined node, allowing validation of the callers identity and ensuring correct billing. Embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings of which: Figure 1 is a schematic diagram of a communication system according to a first embodiment of the present invention; Figure 2 is a block diagram showing the internal structure of a communication terminal according to the first embodiment of the present invention; Figure 3 is a block diagram of the contents of the ROM of the communication terminal illustrated in Figure 2; Figure 4 is a block diagram showing the internal structure of a routing device according to the first embodiment of the present invention; Figure 5 is a block diagram of the contents of the ROM of the routing device illustrated in Figure 4; Figure 6 is a block diagram of the contents of the RAM of the routing device illustrated in Figure 4; Figure 7 is a flow chart indicating the sequence of events when a user operates a communication terminal as illustrated in Figure 2; Figure 8 is a flow chart indicating the sequence of events when a routing device as illustrated in Figure 4 is contacted by an originating terminal; Figure 9 is a flow chart indicating the sequence of events when the communication terminal as illustrated in Figure 2 carries out an authentication procedure; Figure 10 is a flow chart indicating the sequence of events when a routing device as illustrated in Figure 4 carries out an authentication procedure; Figure 11 is a schematic flowchart illustrating operation of a further embodiment of a telephone in accordance with the present invention in which no authentication procedure is carried out; Figure 12 is a schematic circuit diagram of a telephone; Figure 13 is a schematic external view of the telephone of Figure 12; Figure 14 is a schematic flowchart illustrating operation of a telephone as disclosed in Figures 12 and 13; Figure 15 is a schematic representation of a further embodiment comprising a mobile telephone; and Figure 16 is schematic flowchart illustrating operation of a mobile telephone as disclosed in Figure 15. A first embodiment will now be described with reference to Figure 1. The communication system shown in Figure 1 comprises a number of communication networks 5a, 5b, 5c, each of which is connected to a number of local exchanges 3. Figure 1 is schematic and is not intended to indicate that the local exchanges 3 are distinct from networks, since the local exchanges 3 themselves form part of one or more of the networks 5a-5c. A number of telephones 1 are connected via respective signal lines 101 to each of the local exchanges 3. An intelligent node 7 is connected to the networks 5a, 5b, 5c. Located at the intelligent node 7 is a routing device 70 which is operated by a service provider. When a telephone la of a subscriber to the service provider is connected to the intelligent node 7 , the routing device 70 is able to route a call from the subscriber to any other desired telephone lb-lg via one or more particular networks 5a-5c to which the service provider has access . In this embodiment, the service provider requires a subscriber to maintain an account in credit, and throughout a telephone call debits the cost of the call from the subscriber's account. If, during a call, the credit level of the subscriber approaches a minimum credit level a warning signal is sent to the subscriber from the intelligent node 7. If the credit limit is reached the call is cut off. When a subscriber at a telephone la wishes to call a telephone le, the telephone la, in the absence of user intervention, responds to the user lifting the handset of the telephone la and a subsequent dial-tone issued by the local exchange 3 by automatically sending a first dialling signal, corresponding to the telephone number of the intelligent node 7, to the local exchange 3 to which the telephone la is connected via the signal line 101 thereby connecting the telephone la to the intelligent node 7. An authentication procedure, described in greater detail below is then automatically effected by an exchange of encrypted signals between the routing device 70 and the telephone la. The user then manually dials a destination call number identifying the telephone le resulting in a second dialling signal corresponding to the destination call number being subsequently sent from the telephone la to the intelligent node 7. The intelligent node 7 then connects the telephone la to the telephone le, the route of the call between telephone la and telephone le being illustrated by arrows 100 in Figure 1. The networks 5a, 5b, 5c may incorporate any means for transmitting information, for example wires, optical fibres and satellite links . Examples of suitable networks are those provided by telecommunications companies such as British Telecom (Trade Mark) and AT&T (Trade Mark). The Internet is another example of a suitable network. Figure 2 illustrates schematically the components of the telephone la which is shown connected to the signal line 101 by means of a plug 13. The plug 13 fits within a telephone socket and constitutes a connector providing a direct connection to the local exchange 3 via the signal line 101. Two wires for carrying two way signals via the plug 13 are connected to a two to four wire converter 11 via an off-hook switch 15, the two to four wire converter separating in-going and out-going signals on to a pair of output wires 18 and a pair of input wires 20 respectively. The pair of wires from the plug 13 is also connected to a ringer 17 to provide audible indication of incoming calls. The off-hook switch 15 has contacts which are closed when the telephone is actuated, typically by the user lifting a handset prior to dialling, and the contacts being open when the telephone is not in use, i.e. when the handset is replaced. The telephone is provided with a microphone 19 and a speaker 21 which are typically mounted in the handset, the microphone 19 being connected to the output wires 18 and the speaker 21 connected to the input wires 20 so that during a telephone call, outgoing signals can be generated by the microphone 19 and incoming signals can be heard by means of the speaker 21. A tone generator 23 is also connected in series with the speaker 21 to the input wires 20 to enable internally generated tones to be delivered to the speaker 21, as described below. A processor 27 controls operation of the telephone and is connected to both the input wires 20 and output wires 18 for the purpose of receiving signals from and outputting signals to the intelligent node 7. Incoming audio signals from the intelligent node 7 are input to the processor 27 by means of a zero-crossing detector 29 connected to the input wires 20, the detector 29 having an output connected to a counter 31 whose output is connected to the processor 27. The zero-crossing detector 29 and counter 31 allow detection of the presence of audio tones received at the input wires 20 and allow the frequency of the audio tones to be detected and then interpreted by the processor 27. The output of the zero-crossing detector 29 alternates between two states each time the voltage at the input to the zero-crossing detector passes from one side of a hysteresis band located around ground to the other. The counter 31 is an edge counter which is connected to receive the output of the zero-crossing detector 29 and which counts the number of times in a predetermined period that an edge occurs in the output signal, the edge being formed when the output signal of the zero-crossing detector alternates between the two levels . The output of the counter 31 is read at 4 s periods by the processor 27 and the counter 31 is then reset, the processor 27 interpreting the output of the counter 31 to detect the audio frequency of signals present on the signal line. The 2 to 4 wire converter 11 includes a summing amplifier to isolate the signal being transmitted by the PSTN and includes a two pole low pass filter to remove high frequency (above 100 kHz) noise and interference. The zero crossing detector 29 comprises a comparator with a small amount of hysteresis whereby the comparator trip threshold is increased by a small amount after each positive output transition and decreased after each negative transition. This arrangement prevents signal noise from causing oscillation as the input signal crosses the threshold region. The processor 27 is able to generate outgoing audio tones for sending information to the intelligent node 7 by means of a Dual-Tone Multi-Frequency (DTMF) generator 25 whose output is connected to the output wires 18. The processor 27 is connected to a keypad 33, a ROM 35, a RAM 37, a clock 39, an ID chip 41 and the tone generator 23. In this embodiment, the components within the dashed square in Figure 2 are incorporated a single unit, namely a PCD33xx family member core device. The ID chip is a Dallas DS2401 which contains a unique 48 bit ID. Figure 3 is a schematic diagram of the contents of the ROM 35. The system manager 51 controls the operation of the telephone 1. The authentication sub-routine 53 is used to verify the identification of the telephone 1 to the intelligent node 7. The encryption table 55 contains an array of 256 memory locations, each memory location storing a random 8-bit binary number. Identical encryption tables are stored in each one of the telephones 1 having a corresponding account with the service provider and in the routing device at the intelligent node 7. The RAM 37 includes working space for the running of the system manager 51. As shown in Figure 4, a routing device 70 at the intelligent node 7 comprises an input port 61 and an output port 63 which are connected via a switching unit 65. The routing device is connected to the networks 5 including local exchanges 3 via both the input port 61 and the output port 63. On each of the input port side and the output port side of the switching unit 65 respective two wire to four wire converters 67, 69 are connected in parallel with the switching unit 65. The two to four wire converters 67, 69 are connected to a routing device processor 71 via respective transmission systems 73, 75 and via respective reception systems 77,-79. The routing device processor 71 is also connected to a ROM 81, a RAM 83 and a clock 85. Included in the input transmission system 73 is a system for transmitting signals to the telephones 1 which will now be described with reference to telephone la in figure 2 when connected to the intelligent node 7. Frequency shift key encoded signals are sent to the telephone la using a binary code in which a "0" is encoded by the routing device as 10 milliseconds of a 800 Hz tone and a "1" is encoded by the routing device as 10 milliseconds of a 2 kHz tone. In this embodiment the counter 31 located in the telephone la counts the number of edges in a 4 millisecond period and thereby the processor 27, by monitoring the number of counts in successive periods, identifies the input as a "0" or a "1". This system provides a simple alternative to including a DTMF receiver in the telephone la at a reduced cost. As shown schematically in Figure 5, the ROM 81 contains a control procedure 91 for controlling the operation of the routing device, an authentication procedure 93 for verifying the identification of the telephone la, a random number generator 95 for generating a random number used in the authentication procedure 93 and an encryption table 97 that is identical to the encryption table 55 stored in the telephone la . As shown schematically in Figure 6, the RAM 83 contains an encryption key look-up table 102, containing data identifying every telephone 1 which has a corresponding account with the service provider and for each such telephone 1 a respective encryption key, and account information 103 detailing the current balance of the account of each subscriber associated with a telephone 1. The RAM 83 also includes working space 105. The sequence of events when a call is made by a user of telephone la will now be described with reference to Figure 7 which shows a number of steps carried out by the system manager 51 for the telephone la and with reference to Figure 8 which shows a number of steps of the control procedure 91 for the routing device at the intelligent node 7. Firstly, at step SI of Figure 7, the terminal goes off- hook. This occurs when a user picks up the handset of telephone la. At this point, the processor 27 activates the tone generator 23 to generate a "comfort" tone to be heard by the user via the speaker 21 while the system is connecting itself to the routing device at the intelligent node 7 and authenticating its identity. In this way, the user does not have to listen to the interchange of signals between the processor 27 and the routing device which occurs at audio frequencies . The telephone la then checks in step S3 whether a first dial tone, which is generated by the local exchange 3 to which the telephone la is connected in response to the telephone 1 going off-hook, is present since an outgoing call cannot be initiated until the local exchange 3 makes this response. If the first dial tone is present then the procedure moves on to step S7. The processor 27 continues to look for detection of the first dial tone during a time-out period measured using clock 39 and advances the procedure to the next step S7 when detection is sensed or the time-out period expires, as represented by steps S3 and S5 in Figure 7. The use of such a timeout procedure is preferable in order to enable the system to function when poor signal line conditions or other operating difficulties prevent normal detection of the first dial tone. In step S7, the processor checks for user intervention, i.e. whether the "#" button on the keypad of the telephone 1 has been pressed by the user within a preset time-out period of two seconds measured from the detection of the first dial tone. If the "#" button has been pressed, then the normal procedure is interrupted and the system manager 51 moves to step S9 in which the comfort tone is removed to be replaced by the first dial- tone generated by the local exchange 3 and the user dials the number of a destination terminal in the conventional manner without accessing the intelligent node 7 or using the services of the service provider. This feature is incorporated to satisfy legal requirements relating to emergency phone calls so that, for example, in the United Kingdom a user may call the emergency services by pressing "#" and dialling "999". If the pressing of the "#" button by the user is not detected in the preset period, i.e in the absence of user intervention, the procedure continues normally at step Sll by automatically telephoning the intelligent node. This is achieved by using the DTMF generator 25 of the telephone 1 to generate a first dialling signal corresponding to a predetermined call number stored in the ROM 35 and which identifies the location of the intelligent node 7. The signal conforms to the lxxx standard (known as the Easy Access Standard) whereby the first digit sent is "1" followed by a number which indicates the location of the intelligent node 7. The routing device at the intelligent node 7 detects connection to the telephone la at step S25 of Figure 8. The routing device further receives information providing a preliminary identification of the telephone la. In this embodiment, the preliminary identification is made using the Call Line Identifier (CLI) system in which a code identifying the telephone number of the originating caller is generated by the local exchange 3. Subsequently, in step S27, the routing device 70 sends a connection confirmation signal to the telephone la in the form of a continuous tone detected in the telephone la by the zero-crossing detector 29 and the counter 31. The system manager 51 of the telephone la checks, in step S13, if the connection confirmation signal is detected. A further time-out period of two seconds is measured from the commencement of this detection checking step and the processor 27 advances control to step S17 when either detection is sensed or the time-out period expires, as represented in Figure 7 by steps S13 and S15. After the routing device has sent the connection confirmation signal in step S27, the control procedure 91 moves on to step S29 in which the authentication procedure 93 is activated. In step S17 of the system manager 51 for the telephone 1, the authentication subroutine 53 is run. The authentication subroutine 53 for the telephone 1 is shown in detail in Figure 9 while the authentication procedure 93 for the routing device is shown in detail in Figure 10. At step S43 of Figure 9, the telephone la sends a start signal using a predetermined DTMF code signal to the intelligent node 7 indicating the start of authentication. The routing device 70 waits for receipt of the start signal, at step S63, and subsequently sends an authentication data signal in step S65 in the form of a frequency shift key modulated tone. An advantage of sending a start signal from the telephone la to the routing device 70 to initiate authentication is that it is easier for a separate procedure to be initiated than to require the telephone la to differentiate between the connection confirmation signal and the authentication data signal. The authentication data signal consists of a header, a cyclic redundancy check (CRC) block followed by a data block. The data block contains a 16-bit random number generated by the random number generator 95. The routing device sends the authentication data signal repeatedly until a response is received from the telephone la. The telephone la waits for the authentication data signal in step S45 by looking for detection of frequency modulated signals using the zero-crossing detector 29 and the counter 31 and checks in step S47 whether an error is present in the received authentication data signal using the CRC block as a check against a CRC calculation based on the data block. If an error is detected in step S47, the authentication subroutine returns to step S45 to repeat detection and error checking of the authentication data signal. If no error is detected in step S47, the authentication sub-routine continues with step S49. In step S49, the processor 27 in the telephone 1 combines the received random number in the data block of the authentication data signal with an encryption key which is formed by the lowest 16 bits of the 48-bit number stored in the ID chip using a logic operation to create an intermediate 16-bit number. The logic operation may be any standard encryption function adopted for the system, typically comprising a predetermined series of simple arithmetic steps. The intermediate 16-bit number is used in step S51 to generate an authentication response signal by using the first eight bits to address the encryption table 55 which outputs the 8-bit number stored at that address to form the first eight bits of the authentication response signal. The second eight bits of the intermediate 16-bit number are then used to address the encryption table 55 in the same way to form the second eight bits of the authentication response signal. The authentication response signal is transmitted by the telephone la to the node 7 in DTMF form. The routing device at the intelligent node 7 calculates, at step S67, an expected authentication response using an identical logic operation to that carried out by the processor 27 of the telephone la to combine the random number in the data block of the authentication data signal with the encryption key for the telephone la . The routing device processor 71 has knowledge of the encryption key for every telephone 1 of a user who subscribes to the service provider and for each authentication process looks up the relevant encryption key in look-up table 102. Subsequently the routing device processor 71 generates the expected authentication response signal using the encryption table 97 which is identical to the encryption table 55. The routing device waits, at step S69, for the authentication response signal and when the authentication response signal is received compares, in step S71, the authentication response with the expected authentication response. If the authentication response is identical to the expected authentication response then the identification of the telephone 1 has been confirmed and the authentication procedure ends . If the authentication response is not identical to the expected authentication response then, in step S73, the routing device processor 71 checks if a maximum number of retries has been exceeded. If the maximum number of retries has not been exceeded then the authentication procedure returns to step S69. If the maximum number of retries has been exceeded then, in step S77, the routing device sends a signal to the telephone la indicating that the routing device could not confirm the identity of the telephone 1 and that the user of the telephone la must place the telephone 1 on-hook again. An advantageous feature of this authentication process is that the routing device processor 71 calculates the expected authentication response while the telephone la is calculating the authentication response. Therefore, when the authentication response signal is received by the routing device 70, the routing device 70 is immediately able to compare the authentication response with the expected authentication response. If the telephone la has been successfully identified in the authentication procedure 93, then the control procedure of the routing device 70 of the intelligent node 7 proceeds to step S31, as shown in Figure 8, in which the routing device processor 71 checks the account information 103 to see if the customer has sufficient credit to make a call. If the customer does not have sufficient credit to make a call then the routing device sends a credit warning signal, in step S33, informing the customer of that fact. If the customer does have enough credit, then the routing device 70 sends a second dial tone to the telephone 1 in step S35. In step S53 of the authentication subroutine for the telephone la, the processor 27 of the telephone la checks if the second dial tone is present. If the second dial tone is present, this indicates that the telephone la has been successfully identified and the authentication subroutine ends. If on the other hand a signal from the routing device 70 indicating that the customer does not have enough credit to make the call is detected, the comfort tone is removed and the credit warning signal is passed on to the user via the speaker 21. If neither the second dial tone nor the credit warning signal are present, then the processor 27 checks at step S55 if a time-out period has expired. If the time-out period has not expired then the authentication sub-routine returns to step S53 to continue checking for detection of the second dial tone. If the time-out period has expired then the authentication sub-routine ends . After the authentication sub-routine, in step S17, the system manager for the telephone la proceeds to step SI9 in which the comfort tone is removed and the user is presented with the second dial-tone prompting the user to dial the phone number identifying the call destination telephone le. When the routing device receives the phone number of the destination telephone le, the routing device processor 71 controls the switching unit 65 to connect the telephone la to the telephone le. Compared with conventional telephones which have a processor and a DTMF generator, telephones in accordance with the present invention require minimal additional components to perform the authentication procedures described above, namely a receiver enabling the telephone to receive signals sent from the routing device. The embodiment described above has been designed with this conversion in mind and by using a zero crossing detector 29 and counter 31 as a receiver this conversion is achieved at low cost while retaining good functionality. Other forms of receiver or low bit rate modems may however alternatively be used. It will be appreciated that in the first embodiment there is no requirement for the destination telephone le to be modified and could be any conventional telephone. In the first embodiment, a preliminary identification of the terminal la is made using the CLI system. The CLI system may however not be available in some local exchanges . In a second embodiment of the invention therefore, the preliminary identification data is stored in the telephone la and sent by the telephone la in DTMF format with the signal for connecting the telephone la to the intelligent node 7. In a third embodiment of the invention, as another alternative, the preliminary identification data is stored in the telephone la and sent along with the start signal. A further embodiment is illustrated in Figure 11 which illustrates in flowchart form operation of a telephone having a circuit diagram illustrated schematically in Figure 12. In this embodiment, a telephone circuit 120 comprises a two to four wire converter, tone generator, DTMF generator, ringer and off-hook detector similar to those described above with reference to Figure 2. The telephone circuit 120 is controlled by operation of a processor 121 which receives user actuated input from a keypad 122. A microphone and speaker 123 are also connected to the telephone circuit 120. The processor 121 is provided with a read only memory 124 and random access memory 125 in which user configuration data 126 is stored, the configuration data including a look-up table 127 containing an access code for directing calls via a service provider, i.e. to a predetermined mode. The processor controls 121 operation of the telephone at step 110 in Figure 11 to detect an off-hook condition being initiated and activates the tone generator to substitute a comfort tone in place of the dial tone provided by the local exchange so that the user is presented with the comfort tone via the speaker 123. The processor 121 then begins a time-out period measure by means of a clock 134 during which the processor awaits detection of actuation by the user of the * key of the keypad 122. If during the time-out period, which in this example is two seconds, the * key actuation is detected at step 112, the processor 121 responds in "user intervention mode" to control the telephone circuit 120 to output to the local exchange the subsequently entered user dialled digits, i.e. without inserting any access code, at step 113. If however the time-out period is detected to have been completed at step 114 without detection of the * key, the processor 121 obtains an access code from the look-up table 127 and outputs the access code at step 115 via the telephone circuit 120. At step 116, the processor 121 then controls the telephone circuit 120 to allow further user dialled digits entered via the keypad 122 to be output thereby resulting in the call being routed via the service provider indicated by the access code to the destination indicated by the user dialled digits. In the embodiment of Figures 11 and 12 as described, no authentication procedure is performed. A further embodiment based on the structure of Figure 12 will now be described using corresponding reference numerals and with reference to Figure 14 which illustrates the mode of operation of the telephone of this embodiment as controlled by the processor 121. Figure 13 illustrates an external view of the telephone of this embodiment, showing in particular the layout of the keypad 122 which includes function keys 128, 129 and 130 designated as FI, F2 and F3 respectively. The keypad 122 further includes numerical keys 131 and a set of six operating keys 132 which provide further operating functions such as last number redial (LNR), microphone muting (mute), and additionally memory control keys SAVE, RECALL, STORE, and memory (MEM) keys for use in entering configuration data as described below. The telephone of this embodiment operates as illustrated in Figure 14 by initially detecting at step 140 the initiation of an off-hook condition in the telephone circuit 120 and detecting at step 141 the first key of the keypad 122 to be actuated by the user. In response to this detection, the processor 121 controls the telephone circuit 120 to mute the dial tone from the local exchange presented to the user so that thereafter the user hears only dial tones generated by key actuation. At step 143, the processor 121 determines whether the first actuated key is the FI function key 128 and, if so, controls the telephone circuit 120 to output dialled digits corresponding to any further numerical keys 131 actuated by the user, thereby enabling the call to be routed to the desired call destination via the local exchange and the convention public service telephone network, without being routed to any selected service provider. This mode of operation therefore corresponds to one of user intervention in which the user, after lifting the handset, depresses the FI function key 128 in order to deliberately bypass the automatic routing function of the telephone. If at step 143, the first actuated key is detected not to be FI, the processor 121 determines at step 145 whether the first actuated key is F2 function key 129, and if so, at step 146 accesses the look-up table 127 to obtain an access code ACl of a first service provider and controls the telephone circuit 120 to insert the access code ACl before outputting at step 147 further user dialled digits defining the destination of a call. If at step 148, the first key to be actuated is detected to be a numerical key " having a value in the range 2 to 8, the processor 121 similarly at step 146 uses the access code ACl to direct the call via the first service provider. In this way, in the absence of user intervention (i.e. if no function keys are pressed), local calls having the first digit in the range 2 to 8 are automatically routed via the first service provider, without the user having to press any selection key for this purpose, and without the user having to dial any access code. This mode of operation is similar that described above with reference to the telephone embodiment of Figure 11. If however at step 149, the first actuated key is detected to be number "0", the processor 121 awaits detection of the second key actuation at step 150 before deciding at step 151 on the resulting mode of operation. If at step 151 the second actuated key is a number other than "0", the user dialled call is determined to be a national call which is to be routed via a second service provider. In this mode, at step 152, the processor 121 accesses the look-up table 127 to determine the access code AC2 of the second service provider and controls the telephone circuit 120 to insert the access code AC2 before facilitating at step 147 the output of the user dialled digits to follow the access code. The national call required by the user is thereby routed to the destination required via the second service provider. If at step 151, the second actuated key is detected also to be a "0", the processor 121 determines the call to be an international call to be routed by the third service provider. The look-up table 127 is accessed at step 153 to determine the access code AC3 of the third service provider and the processor 121 controls the telephone circuit 120 to insert the access code AC3 before the further step 147 of outputting the user dialled digits. The International call is thereby routed to the destination defined by the user dialled digits via the third service provider. If however at step 154, the first actuated key is detected to be the F3 function key 130, the processor 121 operates in a mode in which a telephone call is automatically mode to a customer service point by dialling a service call number. In this mode, at step 155, the processor 121 accesses the look-up table 127 to determine the service call number and controls the telephone circuit 120 to dial the service call number and connect the user with the customer service point. If at step 156, the first actuated key is detected as being a numerical key of number 1 or 9, the processor 121 allows the user dialled digits to be directed to the local exchange without insertion of any access code, thereby allowing emergency calls to be processed by the user dialling 999 and special function provided by the public service telephone network by dialling numbers commencing with numeral 1 to be accessed. In use, the user is provided with a telephone which is simple to use and yet provides the advantages of automatic routing to preferred service providers for local calls, national (long distance) and international calls respectively without necessarily having to press any keys other than the numerical keys of the telephone number defining the call destination. If for example the number dialled is a local call, for which the first dialled number is in the range 2 to 8 , the telephone automatically inserts access code ACl at step 146 before outputting the user dialled digits, without the user having to press any function key of the telephone. If alternatively the user dials a long distance (national call) for which the first dialled digit is "0" and the second dialled digit is a number other than "0", the telephone automatically inserts the second access code AC2 at step 152 before outputting the user dialled digits at step 147, the call thereby being routed by the second service provider network without the user having to press any function keys or dial any number other than that of the destination call number. Alternatively, if the dialled number is an international call number commencing with digits "00", the telephone automatically inserts the access code AC3 at step 153 before outputting the user dialled digits at step 147, thereby automatically routing the call via the third service provider network without the user having to press any function key or dial any number other than that of the destination call number. The user is however provided with further options to improve flexibility in use of the telephone so that the automatic routing function can be bypassed by user intervention simply by actuating the FI first function key 128, the telephone thereby at step 144 outputting the dialled digits without any access code being added. The user has a second option of initially actuation the F2 second function key, in which case the first access code is automatically inserted, irrespectively of whether the call is a local call, long distance call, or international call, at step 146, before outputting the user dialled digits at- step 147. Finally, a third option is provided of automatically connecting the user to a service point. The user in this instance simply actuates a single key, i.e. the F3 third function key 130 and the telephone responds by automatically dialling the telephone number to access an operative at the service point at step 156. In the above description with reference to Figure 14, the numerical values in steps 148, 149 and 156 are specific to operation within the United Kingdom. It is to be understood that for operating in other countries where reserved numbers for emergency services and public service telephone network special services may be different, the numbers utilised will need to be varied appropriately. The telephone is therefore configurable by the input of appropriate data to the user configuration data 126 portion of the random access memory 125 in Figure 12. This in information may be programmed into the telephone at the time of manufacture or may be updated by the user using the keypad 122 using the operating keys 132 in a predetermined sequence in conjunction with the numerical keys 132 for the input of data. Similarly, the data stored in the look-up table 127 for the first, second and third service provider access codes ACl, AC2 and AC3 may be preprogrammed at manufacture or input or updated by the user using a predetermined sequence of operation of the operating keys 132 and using the numerical keys 131 to input data. Optionally, to assist the user in this configuring mode, the telephone may include a display 133 as illustrated in Figure 12 in order to confirm to the user the data input and the status of the stored information. Such a display may also indicate dialled numbers or other information during normal use. Figure 15 illustrates a further alternative embodiment in which the telephone is constituted by mobile telephone 150 having an aerial 151 facilitating wireless communication with a cellular mobile telecommunications network. The internal structure of the mobile telephone 150 corresponds to the arrangement illustrated in Figure 12, subject to the telephone circuit 120 including a transmitting and receiver for wireless communications and being connected to the aerial 151. As illustrated in Figure 15, the mobile telephone 150 includes numerical keys 131 facilitating the input by the user of a number representing the destination of a telephone call, a call start button 155 and a call end button 156. The mobile telephone 150 includes additional operating keys 152 which provide conventional operating functions of mobile telephones, including access to a menu of additional user functions, interactive access being facilitated by display screen 133. The additional operating keys 152 thereby provide multiple functions selected according to a displayed menu. In use, operation of the mobile telephone 150 is similar to the method described above with reference to Figure 14. In step 140 however, reference to detecting the off- hook condition corresponds to detection of actuation of the call start button 155 of the mobile telephone to initiate dialling and reference in step 141 to detecting the first key actuation is to be understood as a reference to subsequently detecting the first key actuation of the numerical keys 131. Further, it is apparent that in the case of the mobile telephone 150, the signal representative of the destination of the telephone call is output as a wireless communications signal 153 for reception by a receiving aerial of a wireless communications system for ongoing connection to other networks such as the public service telephone network. The mobile telephone 150 provides the facility of user intervention by operation of the additional operating keys 152. If the user decides to intervene in order to prevent the automatic insertion of an access code by the mobile telephone, the user selects display of the menu of functions by depressing whichever one of the operating keys 152 is assigned for this purpose by the mobile telephone manufacturer. The display screen 133 then displays the currently selected function and the user may scroll through the menu of functions in order to arrive at the function described as intervention to prevent automatic insertion of a routing access code. for convenience, this function may be arranged to be the first displayed function when the menu button is initially pressed. To signal user intervention, the user then depresses whichever of the operating keys 152 is assigned for this purpose, the display screen 133 indicating to the user the correct button for this purpose. If the user then proceeds to initiate a call by depressing the call start button 155, the mobile telephone 150 outputs subsequently user dialled digits without adding an access code. The user intervention function selected via the menu may additionally provide the user with selectable options corresponding to the F2 and F3 buttons on the telephone described above with reference to Figure 13 in order to provide functions corresponding to those described above with reference to Figure 14. The functions provided by the mobile telephone may thereby for convenience be referred to as functions FI, F2 and F3 in order to emphasise the commonality of function with the previously described embodiment. Figure 16 illustrates in flowchart form the operation of a computer program of the mobile telephone 150 using corresponding reference numerals to those of Figure 14 where appropriate for equivalent steps . Such a computer program for implementing the steps of Figure 16 constitutes an additional aspect of the present invention, including an embodiment of the program in a storage medium or in electronic form such as a signal transmitted by a network for subsequent installation in a mobile telephone. At step 140 in Figure 16, the processor detects initiation of a telephone call by depression of a call start button 155. In steps 143, 145 and 154 in Figure 16, the processor checks in RAM whether the user has selected any one of the functions FI, F2 and F3 prior to initial actuation step 140. It is therefore apparent that operation of the mobile telephone 150 by the user differs from actuation of the telephone of Figure 13 since, if the user requires intervention, the intervention function must be set prior to step 140 in which the call start button 155 is pressed . A number of modifications can be made to the above- described embodiments without departing from the inventive concept of the invention. Some of these modifications will now be described. The embodiments described with reference to the structure of Figure 12 may additionally include means for performing authentication, as described with reference to the embodiment of Figures 1 to 10. While in the embodiments shown in Figures 2 and 13 the telephone is placed off-hook by lifting up the handset of the telephone la, it will be appreciated that the term "off-hook" is a term of art used to indicate that the telephone la is drawing current from the local exchange 3. Instead of lifting the handset, the telephone 1 may alternatively be placed off-hook by pressing a button or operating a switch, which is the case for telephones with a speaker phone facility and which is also the case for mobile telephones as described with reference to Figure 15. Furthermore, while the embodiments describe a communication system using of a telephone 1 or mobile telephone 150, the same inventive concept could equally be applied to other communication terminals which include a telephone such as, for example, facsimile machines. Alternatively the telephone 1 may be replaced by a private exchange such as private automatic branch exchange (PABX) or a network signal router. In this instance, the off-hook event which initiates the above- described procedures corresponds to an electrical signal generated when a user initiates a call at a terminal connected to the PABX or network signal router. The invention can be applied to cordless telephones having a handset and a corresponding base unit wherein signals are transmitted via radio waves between the handset and the base unit and the base unit is connected to a PSTN using a signal line. Although in the embodiment the service provider requires the subscriber to maintain an account in credit, the inventive concept could equally be applied to a system in which a subscriber has a debit account with the service provider. It will be appreciated that rather than using the combination of the zero-crossing detector 29 and the counter 31 as a receiver in the first embodiment, a DTMF detector could be used and all the communication between the routing device and the telephone la may be carried out using DTMF signals. Preferably the start signal and the preliminary identification information could be sent using the DTMF tones corresponding to ABCD. This is preferable as most telephones do not have ABCD keys and hence the tones could not be input manually, thus providing an extra layer of security. In the first embodiment the telephone la checks to see if there is a first dial tone present before starting the period in which the telephone la checks if the "#" button is pressed. However, as connections to the local exchange 3 for the telephone la typically occurs in less than two seconds, the telephone la may simply check for a predetermined period after going off-hook if the "#" button is presses and not check if the first dial-tone is present at all. Similarly, rather than checking if the connection confirmation signal is present before sending the start signal, the telephone la could simply wait for a preset period of, for example, ten seconds as the vast majority of connections to the intelligent node 7 will be made in this time. The identification number may alternatively be stored in the memory attached to the processor 27 thereby obviating the need for the ID chip 41. As explained previously, the tone generator 23 is only present to provide a "comfort" tone to the user and may be left out if this facility is not required. The described authentication procedure can be varied in many ways without departing from the inventive concept of the invention. One particular variation may be that the routing device 7 sends an error detection and correction block containing, for example, a Hamming code instead of the error detection block containing the CRC block. Other types of signal modulation such as pulse code modulation of a 2kHz tone may be used for transmitting data from the node to the terminal 1.

Claims: CLAIMS 1. A telephone comprising; dialling means (120) operable to output a dialled number in the form of a signal representative of a destination of a telephone call; control means (121) operable to control operation of the dialling means; a keypad (122) responsive to user actuation to input a user generated call number to the control means; route determining means (121,127) selectively operable to determine an access code for routing the telephone call via a preferred route; the keypad comprising a user intervention means (128) responsive to user actuation to signal to the control means a user intervention condition; wherein the control means is operable in the absence of said user intervention condition being signalled to control the dialling means to output a dialled number including the access code determined by said route determining means followed by the user generated call number; and wherein the control means is operable in response to said user intervention condition being signalled to control the dialling means to output a dialled number comprising only the user generated call number. 2. A telephone as claimed in claim 1 wherein the user intervention means comprises a first function key (128)of said keypad. 3. A telephone as claimed in any preceding claim wherein the route determining means and control means are housed unitarily with the dialling means and the keypad. 4. A telephone as claimed in any preceding claim wherein the route determining means is operable to detect initial digits of the user generated call number, further comprising selection means (121) operable to select an access code from a plurality of access codes in dependence upon the detected initial digits . 5. A telephone as claimed in claim 4 wherein the selection means is operable to select one of; a first access code responsive to the initial digits being representative of a local call; a second access code responsive to the initial digits being representative of a long distance call; and a third access code responsive to the initial digits being representative of an international call. 6. A telephone as claimed in any of claims 4 and 5 wherein the route determining means is responsive to actuation of a second function key (129) of said keypad to determine the access code to be a preselected code. 7. A telephone as claimed in any preceding claim wherein the control means is responsive to actuation of a third function key (130) of said keypad to control the dialling means to output a dialled number comprising a predetermined call number representative of a predetermined call destination. 8. A telephone as claimed in any preceding claim comprising memory means (126) storing configuration data accessible by said route determining means to determine the access code and wherein the control means is responsive to actuation of further operating keys of the keypad to update the configuration data stored in the memory means . 9. A telephone as claimed in any preceding claim comprising timing means (134) operable to define a timeout period measured from detection of an off-hook condition and wherein the control means is operable to control the dialling means to output the access code only if the time-out period has elapsed without a user intervention condition having been signalled to the control means . 10. A telephone as claimed in any preceding claim comprising authenticating means (53) operable to receive an authentication data signal and to generate and output an authentication response signal to confirm the identity of the telephone. 11. A telephone as claimed in claim 10 comprising encryption means (55) operable to encrypt the received authentication data signal using a predetermined encryption procedure and an encryption key, whereby the authentication means is operable to generate the authentication response signal from the encrypted authentication data signal . 12. A telephone as claimed in any preceding claim having means for connection to a signal line for transmission of said signal representative of said destination of said telephone call . 13. A telephone as claimed in any of claims 1 to 11 comprising a mobile telephone (150) operable to output said signal representative of said destination of said telephone call as a wireless communications signal (153) . 14. A method of operation of a telephone comprising the steps of; receiving the input of a user generated call number in response to user actuation of a keypad; outputting (147) a dialled number in the form of a signal representative of a destination of a telephone call by operation of a dialling means; controlling operation of the dialling means; selectively operating (146,152,153) a route determining means selectively to determine an access code for routing the telephone call via a preferred route; determining (143) whether a user intervention signal is received in response to user actuation of the keypad to signal a user intervention condition; and controlling the dialling means such that, in the absence of said user intervention condition being signalled, the dialling means (146,147) outputs a dialled number including the access code determined by said route determining means followed by the user generated call number; and such that, in response to said user intervention condition being signalled, the dialling means outputs (144,147) a dialled number comprising only the user generated call number. 15. A method as claimed in claim 14 wherein the intervention condition is signalled in response to user actuation of a first function key (128) of said keypad. 16. A method as claimed in any of claims 14 and 15 wherein the dialling means is controlled by a control means (121) housed unitarily with the route determining means, the dialling means and the keypad. 17. A method as claimed in any of claims 14 to 16 wherein the route determining means detects initial digits of the user generated call number and selects (146) an access code from a plurality of access codes in dependence upon the detected initial digits . 18. A method as claimed in claim 17 wherein the selection step selects one of; a first access code in response to the initial digits being determined (148) to be representative of a local call; a second access code response to the initial digits being determined (149) to be representative of a long distance call; and a third access code in response to the initial digits being determined (151) to be representative of an international call . 19. A method as claimed in any of claims 17 and 18 wherein the route determining means responds (145) to actuation of a second function key (129) of said keypad to determine (146) the access code to be a preselected code. 20. A method as claimed in any of claims 14 to 19 wherein the dialling means is controlled in response to actuation of a third function key (130) of said keypad to output a dialled number comprising a predetermined call number representative of a predetermined call destination. 21. A method as claimed in any of claims 14 to 20 comprising storing configuration data in a memory accessible by said route determining means to determine the access code and updating the configuration data stored in the memory means in response to actuation of further operating keys of the keypad. 22. A method as claimed in any of claims 14 to 21 comprising the further step of measuring (144) a time-out period from detection of an off-hook condition and controlling the dialling means to output (115) the access code only if the time-out period has elapsed without a user intervention condition having been signalled. 23. A method as claimed in any of claims 14 to 22 comprising the further step of. receiving an authentication data signal and generating and outputting an authentication response signal to confirm the identity of the telephone. 24. A method as claimed in claim 23 comprising the further step of encrypting the received authentication data signal using a predetermined encryption procedure and an encryption key, and wherein the generating step generates the authentication response signal from the encrypted authentication data signal. 25. A method as claimed in any of claims 14 to 24 including the step of connecting the telephone to a signal line and transmitting said signal representative of said destination of said telephone call via said signai line. 26. A method as claimed in any of claims 14 to 24 wherein said telephone is a mobile telephone (150) and including the step of outputting said signal representative of said destination of said telephone call as a wireless communications signal (153). 27. A computer program comprising computer implementable instructions for controlling a telephone to carry out a method as claimed in any of claims 14 to 26.

Inventors: DE BEER LEON, DE BEER, LEON
Applicants: BEER LEON DE, PATHFINDER TECH RESOURCES LTD, DE BEER, LEON, PATHFINDER TECHNICAL RESOURCES LIMITED
Application year: 1999
Main classification: H04M3
IPC codes: H04M1, H04M3