WO1992011725A1

WO1992011725A1 - A telecommunications terminal

Info

Publication number: WO1992011725A1
Application number: PCT/AU1991/000588
Authority: WO
Inventors: Brian William Jagger
Original assignee: Telstra Corporation Limited
Priority date: 1990-12-21
Filing date: 1991-12-20
Publication date: 1992-07-09
Also published as: IE914503A1

Abstract

A telecommunications terminal (6) for originating a call, comprising means (48) for storing charging data, and means (20) for determining a charging rate for a call based on said charging data and the destination number entered for said call, and means (20) for determining the cost of said call on the basis of said charging rate and the duration of said call.

Description

A TELECOMMUNICATIONS TERMINAL

The present invention relates to a telecommunications terminal. More specifically, but not exclusively, the present invention relates to a pay telecommunications terminal, such as a pay telephone. The invention also relates to a telecommunications system which includes a plurality of the terminals and an upgrade centre.

At present, the charge for a telephone call is determined and recorded at the local exchange connected to the calling telephone. The charge rate for the call is determined at the exchange on the basis of two factors, known as the charge step and the charge scale. The charge step is a unit of time and represents the length of the periodic intervals at which a fee is levied against a call. The intervals are relatively short for long distance calls, such as to overseas destinations, and relatively long for close destinations, such as local STD calls. The charge step for a call is determined on the basis of the dialled number of the destination. The charge scale determines the fee which should be incurred, for each charge step, on the basis of the dialled number and, if necessary, the time and the day on which the call is made. For pay telephones, which need to monitor payment received by the phone against the cost of a call, dedicated charging equipment is provided at the exchange to send charge pulses to the pay telephone along the line connected to the phone. The charge pulses are representative of the charge rate for a call and enable a pay telephone to determine the charge for a call which has been incurred during progress of the call. The inherent disadvantage associated with the pay telephones in the system described above is installation of the pay phones is relatively expensive and cumbersome as, in addition to the phone being connected at its location to a line, the dedicated charging equipment needs to be installed at the local exchange and connected to the line. Hence, it would be desirable to provide a telephone which can be installed by connection to any normal subscriber telecommunications line without the need for installation of the charging equipment. It would also be desirable to have a pay telephone which can record information regarding status and use, and/or issue appropriate alarm signals when it experiences a component failure.

In accordance with the present invention there is provided a telecommunications terminal for originating a call, comprising means for storing charging data, and means for determining a charging rate for a call based on said charging data and the destination number entered for said call, and means for determining the cost of said call on the basis of said charging rate and the duration of said call.

The present invention also provides a pay telecommunications terminal comprising: means for storing charging data; means for determining a charging rate for a call based on said charging data and the destination number entered for said call; and means for collecting payment for said call on the basis of said charging rate and the duration of said call.

Preferably said terminal includes means for receiving updated charging data from an upgrade centre and storing said updated data in said storing means.

Preferably data received from said upgrade centre is encrypted on the basis of encryption data corresponding to said terminal.

Preferably said terminal includes means for transmitting status and/or alarm data to a management centre.

Preferably said transmitting and receiving means are coupled to a telecommunications line.

The present invention further provides a telecommunications system comprising an upgrade centre and a plurality of said terminals, said upgrade centre including means for producing and transmitting updated charging data to said terminals.

Preferably said upgrade centre includes means for comparing stored current charging data with charging data of a charge management system and, if a variance exists, adjusting said current charging data to comply with said charging data of said management centre so as to thereby form said updated charging data.

Preferably said upgrade centre includes means for storing respective reference data on said terminals and means for verifying the validity of said terminals on the basis of said reference data. Preferably said upgrade centre includes means for adjusting said reference data on relocation of one of said terminals.

Preferred embodiments of the present invention, will now be described, by way of example only, with reference to the accompanying drawings, wherein:

Figure 1 is a block diagram of a preferred embodiment of a pay telephone system;

Figure 2 is a block diagram of a preferred embodiment of a pay telephone; Figure 3 is a flow diagram of a charging procedure executed by the telephone;

Figure 4 is a flow diagram illustrating a procedure executed on installation of the pay telephone;

Figure 5 is a flow diagram illustrating a general procedure executed by an upgrade centre of the system; Figure 6 is a flow diagram illustrating a procedure executed by the pay telephone to receive data from the upgrade centre; and

Figure 7 is a flow diagram illustrating a procedure which is executed on maintenance of the pay telephone.

A pay telephone system 2, as shown in Figure 1, includes an upgrade centre 4 and a plurality of pay telephones 6 connected to the upgrade centre 4 by the Public Switched Telecommunications Network (PSTN). The telephones 6 include processing circuitry and software, as described hereinafter, which enables each telephone to calculate the charge incurred by calls made on the telephone. Calculation of the charge incurred is performed during the progress of a call on the basis of the destination number entered by the person making the call and charging information stored in the telephones 6. The charging information includes charge step data which relates to all the zones which can be called and charge scale data for the different fees to be applied given the time and date on which the call is made. The telephones 6 further include calendar data and real-time clock circuitry, which together with the charge step and charge scale data, enables the processing circuitry of the telephone 6 to determine the correct charge to be levied against a call. The telephones 6 can therefore calculate call charges without the need to receive charge pulses from an exchange. Installation of one of the telephones 6 is therefore considerably simplified as they can be connected to any available subscriber line of the PSTN. The telephones 6 also provide the added advantage that as the charge rate for a call is no longer dictated by a common exchange, the telephones may each store unique charging information which enables charge rates to be applied according to the preferences of the owner, or customer. For instance, a hotel may wish to increase the fee charged for overseas calls, or vary the charge step for such calls after a predetermined period. The telephones 6 also include a status and alarm reporting capability. Status and alarm data, such as coin till full, coin runway jam, coin tube jam, handset broken, and memory failure, are sent by the telephones to a management centre (not shown) via the PSTN.

The upgrade centre 4 is provided to ensure the charging information stored in the pay phones 6 is correct and up to date. The centre 4 includes at least one personal computer 8, such as an IBM 386, and a modem and line interface circuit 10 which enables the centre 4 to communicate with the pay phones 6 via the PSTN. The centre 4 may also include additional storage capacity in the form of a WORM drive or a CD ROM drive. The upgrade centre 4 establishes and maintains a reference file on each of the pay phones 6 in the network. The reference file includes information about a respective phone, such as: 1. The customer's name.

2. The customer's intended or actual telephone connection number.

3. The customer contact number.

4. Serial number of telephone.

5. Serial number of main circuit board of the telephone. 6. Random 10 digit security number allocated to the phone.

7. Physical location.

8. District Office responsible for the phone.

9. Time and day allocation which the phone reports to the management centre. 10. Date of rental purchase.

The reference files can be accessed and adjusted by the District Offices 12 responsible for the phones 6 on receipt of relevant information at the Offices 12 which necessitates a change to a reference file.

A Charge Management System (CHARMS) is presently provided on the Australian PSTN which includes all of the recent and current data in relation to zoning and charging for the PSTN. The information from CHARMS 14 is supplied by a network transmission system, known as TACONET 16, to the upgrade centre 4. The CHARMS data received is stored in the centre 4 and compared daily with the current charging data stored in the upgrade centre 4, on a zone by zone basis. If any changes or variation exist, the date and effect of the changes is determined by the centre 4 and upgrade data is created and appended to upgrade files 18 which respectively relate to the phones 6. An upgrade file 18 includes records such as: 1. Customers intended or actual connection number.

2. Serial number of the telephone 6.

3. Random 10 digit security number allocated to the telephone. 4. Priority allocated to the phone for contacting the management centre.

5. Date after which the upgrade should be affected.

6. Priority allocated in relation to urgency of upgrade.

7. Coded list of data segments within the memory of the telephone 6 which require change.

The upgrade files 18 are used by the upgrade centre 4 to affect upgrades, when required, to the charging information stored in the phones 6, so as to reconfigure the phones by adjusting the charge step and charge scale data accordingly. The scope of changes which the upgrade centre 4 caters for includes telephone number prefix changes, area code changes, International Direct Dial code changes, zone boundary changes, time scale changes, State daylight saving changes, adjustment of internal timing parameters and tariff changes.

Additional files established and maintained by the upgrade centre 4 include an

Initial Data Dump Request file, a Maintenance Staff Data Dump Request file, and a Customer Request file. Both of the Data Dump files have a similar structure to the upgrade files and are used to load data onto the telephones 6 during installation or maintenance procedures, as described hereinafter. The maintenance file is requested by maintenance staff and will include different serial and random security numbers to that of the telephone listed in the corresponding reference file when the main circuit board needs to be replaced. The Customer Request file is created mainly at the responsible District Office or the management centre on receipt on information from a customer relating to a requested alteration or modification to the customer's phone. Data relating to the modification is derived from the Customer Request file and appended to the corresponding upgrade file 18 of the customer's phone 6.

A Calendar file is also be maintained by the upgrade centre 4 which provides time and date information for the upgrade centre and includes information relating to daylight saving changes for each State.

The telephones 6, which may be hereinafter referred to as IBPs, include, as shown in Figure 2, a control logic circuit 20, which is used to control and receive control instructions from a plurality of peripheral units, including a modem 22 which enables the control logic circuit 20 to communicate with the upgrade centre 4 via a speech circuit hybrid 24 and a line interface 26. The line interface 26 of the phone 6 is a two wire interface to a telecommunications line 28 and provides power and signal paths into and out of the phone 6. The line interface 26 is connected to a tone ringer 30 for ringing the bell of the phone 6, a line reversal detector 32, an incoming call detector 34 and a power supply storage circuit 36 which provides power signals to the logic circuit 20. The line interface 26 is also connected to a handset driver 38, via the hybrid 24, which provides an interface for the microphone and the receiver of the handset of the telephone 6.

A hookswitch circuit 40 enables the logic circuit 20 to determine when the phone is "off hook". A cash box switch 42 indicates to the logic circuit 20 when the cash box of the phone is removed, and owner and program switches 44 and 46 enable manual and software reset of the logic circuit 20. The logic circuit further communicates with a charge table memory 48, a decadic pulse dialler 50, a tone dialler 52, a display driver 54, a keypad driver 56 and a real-time clock and calendar circuit 58, which provides real-time information for use by the logic circuit 20.

The telephone 6 also includes a credit tone generator 60 for providing credit warning pulses to the handset driver 38, a pay phone identification tone generator 62, a validator driver 64, and a runway driver 66. The validator driver 64 provides an interface to the validator of the phone which is used to determine the validity of coins inserted into the phone 6. The runway driver 66 has three parallel inputs for a coin tube jammed detector, a till switch and a coin runway jammed detector. The driver 66 also has three parallel outputs, one for a cash gate solenoid, another for a refund flipper and the third for two LEDs which relate to the coin tube and runway jammed detectors.

The control logic circuit 20 includes a microprocessor, RAM and an EPROM for storing all the operating software of the circuit 20. The control logic circuit 20 performs the following functions:

(a) Analysis of the digits entered or dialled on the keypad of the phone 6 which is connected to the keypad driver 56.

(b) Calculation of all charges on the basis of charge step data and charge scale data stored in the charge table memory 48 and the real-time information provided by the real-time circuit 58.

(c) A selection of signal source to be applied to the line 28. The source may be selected from the microphone of the phone, the modem 22, the pulse dialler 50, the tone dialler 52 or the pay phone identification tone generator 62.

(d) Generation of data to be displayed in the liquid crystal display, via the display driver 54, in response to stimuli from the user, the phone itself or the remote management or upgrade centres.

(e) Control of the pulse and tone diallers 50 and 52.

(f) Application of credit expiry tone to the earpiece of the phone using the credit tone generator 60.

(g) Setting of the real-time circuit 58.

(h) Detection and control of low voltage conditions.

(i) Control of the modem 22.

(j) Control of the runway and the coin validator via the drivers 64 and 66.

A charging routine 250 of the telephone 6, as shown in Figure 3, is stored in the EPROM of the telephone 6, as is the case for all routines of the phone 6 described hereinafter. The routine 250 begins at step 252 when a user begins entering a telephone number into the phone 6 in order to make a call. When the first digit of the number is entered, or dialled, the first column of a Digit Analysis Table (DAT) stored in memory of the phone 6 is scanned until a match is found in at least one row of the table. This continues across the subsequent columns of the table in the matching rows or row for each subsequent digit dialled, via a loop 254 of the routine 250, until the scanning digit matches the hexadecimal number F which indicates a digit code corresponding to the telephone number has been found. When the code has been located at step 256, a corresponding charge table index is accessed from the DAT and operation of the routine 250 proceeds from the loop 254 to step 258 where the charge table index is examined. The digit code is normally located before all of the dialled numbers are entered. If the index does not relate to a number for which a charge is to be levied, operation proceeds to step 260 otherwise operation proceeds to step 262. At step 260, if the index relates to a barred number, the call is terminated immediately and a suitable message displayed on the phone 6. If the index relates to a free call number, then payment is not collected by the phone and the call is allowed to proceed as for a standard telephone. If the index relates to an invalid number, again the call is terminated and a suitable message displayed.

At step 262, the index is used to access the charge table memory 48 and retrieve charge data which is relevant to the call. The charge data accessed provides charge step information for the call corresponding to the destination number. Next, at step 264, data provided by the real-time circuit 58 is used to access time slot data in the charge table memory 48. The time slot data is used at step 266 to select from the data accessed at step 262, the appropriate charge data which includes the correct fee to be levied against the call according to the time at which the call was made. The charge data selected at step 266 includes the following information:

(a) Initial fee in cents, which is the value to be deducted from the user's credit on answer of the call.

(b) Fee/Pulse in cents, which is the value to be deducted from the user's credit after each meter interval, or charge step. (c) Pulse Count for a first charging period, which is provided to allow for variable rate charging during a call, and specifies the number of meter intervals after which a second charge rate applies.

(d) Time/Pulse #1 in seconds, which is the length of the meter interval at the normal rate for the call.

(e) Time/Pulse #2 is seconds, which is the length of the meter interval for the second rate, if employed.

At step 268, the call is timed and, on the basis of the data obtained, the meter interval is monitored and the charge incurred by the call is determined during the progress of the call. Payment is collected on the basis of the charge incurred. When payment can not be achieved from the outstanding credit attaching to a phone card, the call is terminated. In the case of coins, when payment can not be collected from the outstanding credit attached to the coins already collected, the next coin available is taken. If there is no next coin available, the call is terminated.

An installation routine 70 of the telephone 6, as shown in Figure 4, begins at step 82 when the phone is delivered and connected to a standard telecommunications line 28 of the PSTN. The routine 70 proceeds from step 72 to step 74 and the phone accesses its serial numbers, its 10 digit random security number and the telephone number of the upgrade centre 4. Next, the telephone enters a loop 76 in which it awaits entry of the customer's connection telephone number. Once the customer's number has been entered, the routine 70 exits the loop 76 and at step 78 calls the upgrade centre. At step 80 a check is made to determine whether the call has been successful and if it is successful, the routine 70 proceeds to step 82, otherwise it proceeds to step 84 where the telephone waits for 5 minutes. If the call is still not successful, the routine proceeds to step 86 and a determination is made as to whether the telephone has attempted to call the upgrade centre 4 at a reasonable hour. If it is not an unreasonable hour, the telephone then calls again at step 78, otherwise the telephone waits at step 88 until a reasonable hour is available and then proceeds to step 78. At step 72 the telephone 6 transmits the serial numbers, random security number and the customers telephone number to the upgrade centre and at step 90 discontinues the call to the centre 4. The telephone enters a countdown state at step 92 during which it is prevented from making any further calls to the upgrade centre. The routine 70 then proceeds to steps 94 and 96 during which it monitors the time which has lapsed since the call to the upgrade centre 4 was terminated until the upgrade centre 4 returns the call in order to load data in the phone 6. If the upgrade centre 4 does not return the call within a predetermined period of time, operation proceeds to step 86 from which the centre 4 can be called again, otherwise the phone 6 simply receives the data sent by the upgrade centre 4 and the routine 70 ceases at step 98 on completion of the data transfer. For security purposes, as described hereinafter, the software stored in the EPROM of the phone 6 is reconfigured so the telephone 6 can no longer make any further calls to the upgrade centre 4.

An operating routine 100 of the upgrade centre 4, as shown in Figure 5, may begin at step 102 at which upgrade requests created by customer calls are screened and entered into the system by a system operator, which involves the creation of a Customer Request file. Next, at step 104 information provided in Customer Request files is combined with the corresponding upgrade file together with any of the following information:

1. Initialisation requests from newly connected telephones.

2. Date/Time changes due to State Legislation, i.e. daylight saving changes.

3. Tariff changes.

4. Upgrades required due to variation between the current charging information stored and the charging data provided by CHARMS.

Information from the corresponding reference files is inserted into the upgrade files at step 106. At step 108, the information stored in a reference file of one of the phones 6 is compared with the information provided for any upgrade or request. In particular, the corresponding telephone, serial and random numbers in the reference file is checked against the corresponding upgrade file and if the numbers all correspond, operation proceeds to step 110, otherwise an error is reported at step 112.

The number of the telephone to be called by the upgrade centre 4 is retrieved from the hard disc of the PC 8 at step 110. The corresponding zone for the number is determined at step 113 and at step 114 the appropriate zone file containing coding information relevant to the zone is accessed and appended to the upgrade file containing data to be transferred. A time determination is made at step 116 and at step 118 a decision is made as to whether it is an appropriate time to call the telephone 6 to transfer the data. If it is not an appropriate time, operation returns to step 116, otherwise speech communications software stored in the upgrade centre 4 is retrieved at step 120 and the telephone number is dialled at step 122. At step 124, if the call is answered by the customer, or automatically answered after 12 rings by the telephone itself, operation proceeds to step 126, otherwise if no answer can be achieved, call failure is reported at step 112. A warning tone is sent to the telephone via the upgrade centre, at step 126, advising data is about to be transmitted, and at step 128 the data transfer takes place, according to a predetermined communications protocol between the centre 4 and the phone 6. All data transmitted by the upgrade centre 4 is encrypted, or encoded, on the basis of the ten digit random security number of the phone. The upgrade centre 4 accesses its record of the security number on the basis of the telephone or serial numbers of the telephone 6. Whether the transmission is successful or not is determined at step 130 and a corresponding report is made and recorded at step 112. Operation of the routine then returns to step 108 at which the process is repeated for another telephone 6, if necessary.

A complementary routine 200, to the routine 100 of the upgrade centre 4, is performed by the phone 6, as shown in Figure 6. The routine 200 begins at step 202, when the phone 6 receives a call from the upgrade centre 4. The phone waits at step

204 for a person to answer or automatically answers the call after 12 rings. At step

206, the phone 6 determines whether the special tone transmitted at step 126 of routine 100 has been sent and if no tone can be detected at step 208, the telephone 6 terminates the call at step 210. If the tone is transmitted and a person has answered the phone 6, a recorded speech message is received at step 212 asking the person to replace the receiver so data can be transmitted to the phone 6. At step 214 a determination is made as to whether the person has responded and if the receiver has not been replaced, the telephone 6 simply disables its speech circuits, at step 216 to prevent any audio interference to data transmissions to be received. Once the speech circuits have been disabled, by the receiver being replaced or the procedure of step 216, operation proceeds to step 218. If the telephone has been automatically answered by the phone 6, the telephone 6 responds to the upgrade centre 4 by sending an appropriate recognition tone at step 220, and then operation of the routine 200 proceeds to step 218.

The telephone circuitry, at step 218, prepares the EEPROM of the charge table memory 48 for erasure and activates the modem 22. Data transmission then commences at step 222 and the communications protocol between the upgrade centre 4 and the telephone 6 continues at step 226 until appropriate termination handshake signals are exchanged. At step 228 a determination is made as to whether the data transmission has been successful, and if so the call is terminated at step 230, otherwise the failure is reported at step 232 and the call terminated at step 234.

On relocation of a telephone 6 a customer must request a new telephone number to receive data from the upgrade centre 4. The customer can not simply enter the new telephone number, on relocation, into the telephone 6 and have the telephone send the number to the upgrade centre 4, as the ability of the telephone 6 to call the upgrade centre 4 is disabled, as described previously, on receiving the initialisation data. This prevents stolen telephones from being used in a new area as the upgrade centre 4 will only transmit reconfiguration data to a telephone at a telephone number corresponding to its serial numbers and recorded at the upgrade centre 4 in its reference file.

The management centre receives all alarm messages and status reports sent by the control logic circuits 20 of the telephones. The regular status reports are primarily to indicate how a telephone 6 is functioning and include the telephone and serial numbers of the telephone 6. The management centre is able to detect and locate stolen phones, as reports transmitted by stolen phones will include telephone numbers and serial numbers which do not correspond. The serial numbers are sent by the phones, which on establishing a call to the management centre, cause a calling line identification signal, representative of the calling number, to be sent by the connecting exchange to the centre.

A routine 150 which the telephone 6 executes on installation of a new main circuit board, as shown in Figure 7, begins at step 152 after a technician has physically inserted the new board. The technician enters an appropriate code into the telephone 6 to place the telephone in a maintenance mode. At step 154, the technician enters the serial number of the telephone, as printed on its housing, and the telephone number of the phone 6 at step 154. The new board contacts the upgrade centre at step 156, establishes a call and sends a maintenance mode message to the centre 4. The telephone 6 transmits the telephone number of the customer, the serial number of the phone and the serial number of the new board at step 158. Using the serial number of the new board, the upgrade centre 4 accesses a Unique Data Identifier file at step 160 which includes the serial numbers and random security numbers allocated and communicated to the centre 4 by the telephone manufacturer. The new serial number is checked at step 162 to determine whether the number is within the range of numbers issued and to ensure it is not currently listed as being used. If a negative determination is made at step 162, operation proceeds to step 164 where the telephone 6 is advised and a corresponding display is generated regarding a possible security risk. The call is terminated at step 166 and appropriate reports made. On receiving a positive determination at step 162 the upgrade centre 4 accesses the reference file corresponding to the serial number, at step 168, and at step 170 determines whether the customer telephone number and the telephone serial number correspond. If there is no correspondence, an error code is transmitted and displayed on the telephone 6 inviting the technician to re-enter the telephone serial number at step 172. After re-entry of the customer telephone number and the telephone serial number at step 174, operation of the routine 150 returns to step 156. If the telephone and serial numbers do correspond an encrypted test message is sent from the upgrade centre to the telephone 6 at step 176. If the message is not correctly received the call is terminated at step 178, however, if it is correctly received complete initialisation data is sent to the new board at step 180. On completion of the transmission, the upgrade centre 4 adjusts the reference file corresponding to the telephone so as to record the new board serial number and a new ten digit security number, at step 182, and the routine terminates the call at step 184.

The maintenance routine 150 ensures the security of the upgrade centre 4 and the telephones 6 is maintained on the basis of the telephone serial numbers, the security number and the telephone number for each phone 6.

Claims

CLAIMS:

1. A telecommunications terminal (6) for originating a call, comprising means (48) for storing charging data, and means (20) for determining a charging rate for said call based on said charging data and the destination number entered for said call, and means (20) for determining the cost of said call on the basis of said charging rate and the duration of said call.

2. A pay telecommunications terminal (6) comprising: means (48) for storing charging data; means (20) for determining a charging rate for a call based on said charging data and the destination number entered for said call; and means (20,64,66) for collecting payment for said call on the basis of said charging rate and the duration of said call.

3. A terminal (6) as claimed in claim 1 or 2, including means (20,22,24,26) for receiving updated charging data from an upgrade centre (4) and storing said updated data in said storing means (48).

4. A terminal (6) as claimed in claim 3, wherein said charge data includes charge step data and charge scale data.

5. A terminal (6) as claimed in claim 4, including real-time means (58) for generating time and calendar data for use by said determining means (20) to select charge scale data for said call from said charge data.

6. A terminal (6) as claimed in claim 5, including a digit analysis table stored therein and keypad driver means (56) for providing said destination number to said determining means (20), which accesses said table on the basis of said destination number to obtain a charge table index for accessing said charge data.

7. A terminal (6) as claimed in any one of claims 3 to 6, wherein data received from said upgrade centre (4) is encrypted on the basis of encryption data corresponding to said terminal (6).

8. A terminal (6) as claimed in claim 7, including means (20,22,24,26) for causing transmission of status and/or alarm data relating to said terminal (6) to a management centre.

9. A terminal (6) as claimed in claim 8, wherein said status data is transmitted on a regular basis and includes at least one serial number indicative of said terminal (6) and a telephone number corresponding to the location of said terminal (6), and a theft alarm is issued when said serial and telephone numbers do not correspond.

10. A terminal (6) as claimed in claim 9, wherein said transmitting and receiving means (20,22,24,26) includes a modem (22) and a line interface (26) connected, in use, to a telecommunications line (28).

11. A telecommunications system (2) comprising an upgrade centre (4) and a plurality of terminals (6) as claimed in any one of the preceding claims, said upgrade centre (4) including means (8,10,18) for producing and transmitting updated charging data to said terminals (6).

12. A system (2) as claimed in claim 11, wherein said upgrade centre (4) includes means (8,10) for receiving a customer request to alter the charging data stored in one said terminals (6) and transmitting updated charging data in accordance with said request to said terminal (6).

13. A system (2) as claimed in claim 12, wherein said upgrade centre (4) includes means (8,10) for comparing stored current charging data with charging data of a charge management system and, if a variance exists, adjusting said current charging data to comply with said charging data of said management centre so as to thereby form said updated charging data.

14. A system (2) as claimed in claim 13, wherein said updated charging data is formed in an upgrade file (18) for each terminal (6) which includes a list of memory segments in a respective terminal (6) which require change.

15. A system (2) as claimed in any one of claims 11 to 14, wherein said upgrade centre (4) includes means (8,10) for storing respective reference data (11) on said terminals (6) and means (8,10) for verifying the validity of said terminals (6) on the basis of said reference data (11).

16. A system (2) as claimed in claim 15, wherein said upgrade centre (4) includes means (8,10) for adjusting said reference data (11) on relocation of one of said terminals (6).

17. A system (2) as claimed in claim 15 or 16, wherein said reference data (11) includes at least one serial number indicative of the respective terminal (6) and a telephone number corresponding to the location of said terminal (6).

18. A system (2) as claimed in claim 17, wherein said terminals (6) disable transmission to said upgrade centre from said terminals (6) after installation thereof.