WO2001049060A1

WO2001049060A1 - Apparatus for rerouting calls placed on a mobile telephone

Info

Publication number: WO2001049060A1
Application number: PCT/SE2000/002671
Authority: WO
Inventors: Niclas Carlsson; David LÖWENBRAND
Original assignee: Kreatel Communications Ab
Priority date: 1999-12-28
Filing date: 2000-12-27
Publication date: 2001-07-05
Also published as: AU2420901A; SE9904848D0

Abstract

Methods and apparatus for providing telecommunications services to a subscriber having a mobile telephone. In one aspect, the invention features an add-on accessory configured to connect physically or by wireless connection to the mobile telephone and to communicate with, and control operation of, the mobile telephone through an external interface. In another aspect, the invention features programming for the mobile telephone that includes routing data and rerouting instructions, the programming being operable to change the operational behaviour of the mobile telephone in placing a telephone call requested by a user of the mobile telephone, the programming being further operable to cause a telephone call requested by the subscriber to be rerouted to a subscriber-requested destination through a server connected to a public switched telephone network.

Description

APPARATUS FOR REROUTING CALLS PLACED ON A MOBILE TELEPHONE

BACKGROUND OF THE INVENTION

The present invention relates to apparatus providing services such as call routing functionality to users of mobile telephones.

Mobile telephone equipment and systems have developed according to a number of standards around the world. One such standard is Global System for Mobile communications (GSM). GSM is described specifications produced by the Special Mobile Group (SMG) Technical Committee (TC) of the European Telecommunications Standards Institute (ETSI). GSM Technical Specification (GTS) GSM 7.07, for example, specifies a profile of AT commands and recommends that this profile be used for controlling Mobile Equipment (ME) functions and GSM network services from a Terminal Equipment (TE) through a Terminal Adaptor (TA). An abstract architecture is defined in which a TE (e.g., a computer) and a ME are interfaced by a TA. The span of control of the defined AT commands can handle any physical implementation that this abstract architecture may lead to: the TA, ME and TE as three separate entities; the TA integrated under the ME cover, and the TE implemented as a separate entity; the TA integrated under the TE cover, and the ME implemented as a separate entity; the TA and ME integrated under the TE cover as a single entity. The interface between TE and TA is intended to operate over existing serial (ITU-T Recommendation N.24) cables, infrared link, and all other link types with similar behaviour. The interface between the TA and ME is dependent on the interface in the ME. A mobile telephone (which is referred to as a "ME" in the GSM specifications) generally will have a digital external interface and an analogue external interface. The digital interface generally provides functionality of the kind specified by GSM 7.07 - even in non-GSM equipment and in GSM equipment that does not comply with the specification. The analogue interface generally provides access to the speech channel of the telephone; it is used, for example, to connect analogue modems and hands-free equipment to the telephone.

Conventional wire-connected telephones, whether connected directly to a public switched telephone network or to a private telephone switch, can be used with call routers, such as the Phonix™ call router available from Kreatel Communications AB of Linkδping, Sweden. This call router, for example, is designed to be programmed to provide prefix routing, callback routing, access switch routing, least-cost routing (day- and time-based routing), and other functionality through the services of an alternative telephone carrier. This router can be programmed at manufacture or programming can be downloaded through a built-in modem, to provide initial programming as well as updates. SUMMARY OF THE INVENTION

The invention provides an apparatus including computer programs, for providing telecommunications services to a subscriber having a mobile telephone.

In general, in one aspect, the invention features programming for a mobile telephone. The programming is stored on a tangible medium of expression as digital electronic information that includes routing data and rerouting instructions. The programming can change the operational behaviour of the mobile telephone in placing a telephone call requested by the subscriber and to cause a telephone call requested by the subscriber to be rerouted to a subscriber-requested destination through a server connected to a public switched telephone network. Particular implementations can have one or more of the following features. The programming can reroute the telephone call requested by the subscriber according to environment data provided by the mobile telephone. The programming is embodied in an add-on accessory. The accessory can be configured to connect to the mobile telephone physically or with a wireless interface. The programming is embodied in a personality module configured to be inserted in the mobile telephone. In another aspect, the invention provides an apparatus for providing telecommunications services to a subscriber having a mobile telephone. The apparatus includes programming for the mobile telephone stored on a tangible medium of expression as digital electronic information. The instructions can operate to connect the subscriber transparently through an alternative service provider to a destination telephone number selected by the subscriber on the mobile telephone by placing a call to a server telephone equipment at a telephone number different from the destination telephone number selected by the subscriber. The instructions can include instructions to receive a server telephone number for the server telephone equipment and to store the received server telephone number in a memory physically coupled to the mobile telephone for later use. They can also include instructions operable to receive obtaining environment information from the mobile telephone and to use the environment information to determine whether or not to connect the subscriber to the destination telephone number through the alternative service provider. In another aspect, the invention provides an apparatus for use as an accessory to a mobile telephone that has an external telephone interface for receiving and providing signals. The apparatus includes an accessory interface for coupling the accessory to the mobile telephone. The accessory interface can provide command signals to the mobile telephone and to receive information signals from the mobile telephone. The information signals include signals (i) specifying a destination number, the destination number being a telephone number selected by a user of the mobile telephone, and (ii) indicating that a call request has been made by the user to initiate operations by the mobile telephone to place a telephone call to the destination number; and the command signals include signals for causing the mobile telephone to (i) terminate a call, (ii) place a call to a number specified by the accessory, and (iii) transmit information to equipment answering a call placed by the accessory. The apparatus also includes rerouting memory for storing call rerouting data, the rerouting data comprising data defining one or more methods to be applied when placing a call to a destination defined by the destination number; and rerouting means coupled the accessory interface to receive a destination number and to receive a call request indication, and further coupled to the rerouting memory to read the rerouting data, the rerouting means being operable to select a method defined by the rerouting data and to perform selected method. In particular implementations, the command signals further include signals for causing the mobile telephone to transmit information to equipment answering a call placed by the accessory; and the apparatus further includes rerouting memory for storing call rerouting data, which includes data defining one or more methods to be applied when placing a call to a destination defined by the destination number; and rerouting means coupled the accessory interface to receive a destination number and to receive a call request indication, and further coupled to the rerouting memory to read the rerouting data, where the rerouting means can select a method defined by the rerouting data and perform the selected method.

Advantages that can be realised in or from implementations of the invention include one or more of the following.

The invention is generally applicable to, and can be implemented in, other mobile telephone systems in addition to GSM. The invention can be used for the benefit of the mobile telephone user to take advantage of imbalances between telephone charges from different infrastructure providers, in different jurisdictions, or both. The invention reduces barriers of consumer acceptance to an alternative carrier attempting to enter a mobile telephone market, because the use of the alternative carrier's special prefixes and other calling protocols are invisible to the mobile telephone user. Implementation of the invention in an add-on accessory to a mobile telephone does not change the behaviour of the mobile telephone in any undesirable way; for example, the user can use the phonebook of the mobile telephone, can use a phonebook in a Subscriber Identity Module (SIM), can call back on a missed call, and can use other dialling functions without any change when the accessory is added to the mobile telephone. Implementation of the invention in an add-on accessory does not change the way the mobile telephone connects a call (that is, it does not affect the way the mobile telephone performs Call Control). It also does not compromise the type certification or approval status of the mobile telephone. Implementation of the invention in an add-on accessory allows users to make their own choice of telephone equipment and still use the services provided through use of the accessory.

An alternative service provider (i.e., an alternative carrier) need not compete with infrastructure operators in subsidising the sale of mobile telephones. The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will become apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a add-on mobile telephone accessory in accordance with the invention.

FIG. 2 is a block diagram of a management interface of a mobile telephone accessory in accordance with the invention.

FIG. 3 is flowchart of a method of call rerouting in accordance with the invention.

FIG. 4 and FIG. 5 are each a schematic block diagram illustrating relationships among components of a telecommunications system in which rerouting through an alternative carrier server is used to connect a call from a mobile telephone.

FIG. 6 is a flowchart showing steps of callback methods of rerouting a call from a mobile telephone.

FIG. 7 is a flowchart showing steps of an access switch method of rerouting a call from a mobile telephone.

FIG. 8 and FIG. 9 are flowcharts showing updating methods for updating rerouting information in a mobile telephone accessory.

Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION

FIG. 1 is a block diagram of a add-on mobile telephone accessory 100 in accordance with the invention. The accessory 100 has a digital interface 102 and an analogue interface 104 configured to be connected physically and electrically with any kind of mobile telephone 106, including one configured with a SIM 108. The accessory 100 also has an optional digital computer interface 1 10 to allow communication with a computer such as a personal computer. This computer interface 1 10 can be a wire or wireless interface, such as an infrared or radio frequency interface. In alternative embodiments, the accessory 100 can also be coupled to the mobile telephone 106 through a wireless connection, such as a Bluetooth interface, to provide an interface for digital and analogue data transfer.

Access to the digital interface 102 is made through a number of layers of conventional design, including a telephone hardware interface 1 12 designed for a particular telephone 106 or family of telephones, a hardware abstraction layer 1 14 that provides a standard interface to the hardware, and a telephone driver 1 16.

The analogue interface is used by an optional analogue modem 1 18 and by other optional hardware, such as a hands-free module.

Access to the computer interface 1 10 is made through accessory hardware and interface circuitry 120, which is accessed through a hardware abstraction layer 122.

All of the facilities of the accessory 100 are controlled by a control program 130, which is a small real-time control program that performs such functions as task scheduling and control. The control program 130 is supported by a scheduler 132, a scheduling program module that performs scheduling tasks, by device data 134, a collection of data describing the hardware environment of the accessory 100, and a management interface

136, a program module providing an interface to the digital interface 102 and the analogue interface 104.

The accessory 100 can be programmed to perform call rerouting. Call rerouting transforms a user-selected telephone number - which can be a full telephone number or an abbreviated number - into a different number or a sequence of actions that may involve placing one or more telephone calls and sending or receiving data from one or more sources. In particular, the accessory 100 can be programmed with a rerouting module 140 and supporting routing data 142 to implement a call rerouter and that performs one or more call rerouting methods, such as a callback method or an access switch method, which will be described later.

As shown in FIG. 2, a management interface 136 (also shown in FIG. 1) includes a computer interface manager 202, a program module that provides interface services for the control program 136 to interact with a computer through a computer interface 1 10 (FIG. 1) such as a Universal Serial Bus (USB) interface, a null modem interface, an infrared interface, a Bluetooth interface, or any other wire-based or wireless interface. (Bluetooth is a code name for a technology specification for small form factor, low-cost, short range radio links between mobile PCs, mobile phones and other portable devices .)

The management interface 136 also includes a modem manager 204, a program module that provides interface services for the control program to interact with the analogue modem 1 18 and ultimately with the analogue interface of the mobile telephone.

The management interface 136 also includes a Data Circuit terminating Equipment • Data Terminal Equipment (DCE - DTE) manager 206 and an SMS manager 208. Each provides interface services for the control program to interact with the telephone driver 1 16 and ultimately with the digital interface of the mobile telephone. The SMS manager 208 can be implemented to use the services of the DCE - DTE manager 206.

FIG. 3 shows steps that occur when a user makes a call on a mobile telephone implementing a call rerouter, which can be done in an add-on accessory, as has been described. The user selects a destination number, which may be a local, a long-distance or an international telephone number, or it may be a short number used to call a special service (step 302). The number may be selected by keypad entry, through lookup in a phone book on the mobile telephone, through selection of a redial function, or otherwise. The call rerouter captures the destination number (step 304), which is made available through the digital interface of the mobile telephone. The user then presses the "call" key on the mobile telephone, or presses some other key to initiate calling, which may be the same act that selects a destination number; and the telephone in response initiates a call to the destination number (steps 306 and 308). In some implementations, the call rerouter then intervenes and terminates the call (step 310). After the destination number is known, i.e., after the user has caused the mobile telephone to initiate the call (step 306), the call rerouter selects a calling method (step 312), having previously obtained the destination number (step 304) and, optionally, environment information (step 314). The selection of a calling method is advantageously done using some small database of calling methods (step 316), such as a table that will be described later, to define the selection. Having selected a calling method, the call rerouter connects the mobile telephone to the destination number using the selected calling method (step 318). Two calling methods, a callback method and an access switch method, will now be described.

As illustrated in FIG. 4, a callback method is generally offered by a telephone service provider (SP) 402, such as an alternative carrier, to provide telephone services through facilities alternative to those provided by default through a public switched telephone network (PSTN) 412 or through the infrastructure of a wireless carrier. To implement the callback method, the service provider establishes a Calling Line Indication server (a CLI-server) 406 that is in communication with a callback switch 408 maintained by the service provider. The procedure for a call made from a mobile telephone is as follows. 1) A mobile telephone A 414 operating under control of a call rerouter implemented, for example, as program instructions and data in an add-on mobile telephone accessory, calls a telephone number 404 provided by the service provider and rings the CLI-server 406. The call rerouter makes the mobile telephone be on-hook before the CLI-server 406 answers. The call is made through a wireless carrier base station 410 of a primary carrier from which the mobile telephone A 414 can receive service. The

CLI-server gets the number of the mobile telephone that placed the call from the public switched telephone network 412. In alternative embodiments, the call rerouter can leave the mobile telephone off-hook and provide identifying information to the CLI-server, using dual-tone multifrequency (DTMF) tones, for example, transmitted through the analogue interface 104 (FIG. 1) of the mobile telephone or generated by the mobile telephone in response to commands (such as AT commands) given through the digital interface 102, to encode the information.

2) The CLI-server transmits the number of the calling mobile telephone to the callback switch 408. The CLI-server and the callback switch may optionally be implemented in the same equipment.

3) The callback switch 408 calls mobile telephone A 414, which answers the call. The call rerouter in mobile telephone A is waiting for the call from the callback switch.

4) The call rerouter in mobile telephone A 414 sends the destination number to the callback switch 408, using DTMF tones to encode the information, for example. 5) The callback switch 408 calls the destination number, telephone B. Telephone B can be any kind of telephone, including a mobile telephone 420a or a connected telephone 420b coupled to a private network maintained by the service provider, or a mobile telephone 420c or a connected telephone 420d coupled to any public network 422. 6) If the call to the destination number is answered, the callback switch 408 connects mobile telephone A 414 and telephone B.

As shown in FIG. 6, a number of submethods to a callback method can be implemented. In a user ID submethod 610, the call rerouter (CR) calls the callback switch (CBS) (step 612). The call rerouter transmits validation information such as a user identifier (ID) to the switch (step 614). The router also transmits the destination number and hangs up (step 616). The switch places a call to the destination number and to the user and connects the calls to each other (step 618).

In a dedicated target submethod 620, the call rerouter calls a telephone number specific to the user (subscriber) rather than a general callback switch number (step 622). The switch recognises the user by the number called (step 624). The method continues with step 616, described above.

In a CLI-server submethod 630, the call rerouter calls a CLI-server and then hangs up (step 632). The server gets the callback number (that is, the telephone number of the calling mobile telephone) from the telephone network (step 624) and transmits it to a callback switch. The switch calls the user at the callback number (step 636). The call rerouter answers the call and transmits the destination number to the switch (step 638). The switch calls the destination number and connects the user call and the destination call to each other (step 640).

As illustrated in FIG. 5 and FIG. 7, an access switch method 700 is generally offered by a telephone service provider 502, such as an alternative carrier, to provide telephone services using facilities of the alternative carrier. In a basic implementation of an access switch method, the service provider 502 establishes an access telephone number 504 for subscribers to call. A call to the access number 504 is answered by an access switch 506 established by the service provider 502. Generally, the call to the access number 504 appears free of cost to the subscriber. A call to a destination number selected by the subscriber is completed by a mobile telephone call rerouter according to the following procedure.

1) The call rerouter causes mobile telephone A 508 to call the access number 504 and the call is connected (step 702). The call is made through a wireless carrier base station 510 of a primary carrier from which the mobile telephone A 508 can receive service. Generally, the call is connected through the public switched telephone network 512.

2) After the call is connected (step 704), the call rerouter sends the destination number to the access switch 506, by using DTMF tones, for example (step 710). Optionally, the access switch validates the caller, by using the services of a trusted source of calling line identification or by validating a user identifier and password, such as a dynamically generated password, from the call rerouter (step 710). The operations can be performed in any order, and other operations, such as validating and updating the routing database used by the mobile telephone add-on accessory, can also be performed at this time (step 706). 3) The access switch 506 calls the destination number, telephone B (step 712). The destination number can be on any telephone network, mobile or otherwise. That is, telephone B can be any kind of telephone, including a mobile telephone 514a or a connected telephone 514b coupled to a private network 516 maintained by the service provider 502, or a mobile telephone 514c or a connected telephone 514d coupled to any network 518 or 520.

4) The access switch connects mobile telephone A 508 and telephone B (step 712). The call rerouter can use routing data in the form of a routing table to determine whether and how to reroute a call. In the following example, the table contains information on how the call rerouting should take place depending on the country (a MCC is a Mobile Country Code), network (a MNC is a Mobile Network Code) and area (a LAC is a Location Area Code) where the mobile telephone is located when the call is placed. The information about the location of the telephone is obtained by the call rerouter from the mobile telephone when it is needed.

The structure of an illustrative routing table is shown below.

MCC LAC Method Sub- Server and method Number

MNF

123 77 C CI +44 23 121338

341 ** A Al +46 77 889977

54* ** A Al +45 98 772244

123 88 N 123 ** C C2 +44 65 231233

*** ** N -

The first entry (row) in the routing table shows country and network = 123 and area = 77 . This entry indicates that when the location of the mobile telephone satisfies that condition, the mobile telephone should use the callback method (C) with a first submethod (CI). Telephone number +44 23 121338 should be called to reach the CLI-server.

The second entry indicates that with country and network = 341, the access method (A) should be used, for any area. The telephone number of the access switch is +46 77 889977. The third entry, with country = 54, indicates that the access method should be used, for any network and any area where the mobile telephone may be located.

The fourth column of the table indicates what submethod should be used, if any are available. The fourth entry indicates that no routing should be used for country and network = 123 within area = 88.

The fifth entry indicates that the callback method with a second submethod (C2) should be used for country and network = 123 within any other area (areas 77 and 88 having been provided for in earlier table entries). The last entry implies no routing should be used for that all other country-network- area combinations, as the default case.

In other implementations, additional columns are included in the table to be used to select a routing method, including, for example, time of day, day of week, destination number, parts of destination number such as country code or city code, and so on. In further implementations, additional information is included in the table to use in rerouting a call or exchanging information with an alternative carrier. Such information includes, for example, a user identifier and a user password. Such information can also include a table checksum and a version number.

In addition, the routing table can optionally define a transformation of the destination number. For example, if a destination number is entered as "nnn*xxx" ~ where nnn is the number to be called and xxx is an extension to be entered in response to an automated attendant answering the number nnn - then the call rerouter transmits the number nnn to the callback switch, for example, and then waits until a connection has been made to the destination number, at which time the call rerouter transmits the extension xxx. The rerouting functionality can be activated in a variety of ways.

The routing table and any other variable elements can be installed during production B that is, the accessory can be loaded with the variable information for the service provider before the accessory is packaged and sent to the subscriber. The subscriber can then register his/her subscription with the service provider so updated information can be provided to the accessory.

Alternatively, the subscriber can initiate the downloading of variable rerouting information to the accessory. In an accessory produced for a particular service provider, the accessory can be preloaded with information to call the service provider and obtain rerouting information. In an alternative, generally-purpose implementation, the accessory programming implements a simple user interface responsive to predefined patterns of numbers and the * and # keys. For example, the following commands can be implemented.

Form Meaning *991 *nnnn# nnnn is the telephone number of a server that the mobile telephone can call to initiate service with the service provider. The number can optionally also be the number to call to request updates. *992*aa*bb# aa and bb are parameters B such as an account identifier and a password number B specifying a means of payment. Any number of parameters can be provided. *993*nnnn# nnnn is a number selecting a calling plan, where a carrier has multiple plans, for example. This allows the management system to select the correct routing table where a carrier has multiple tables.

As shown in FIG. 8, the service provider can provide updates in a variety of ways. An update process can be initiated by a call rerouter, by the service provider (SP), or by a user (step 802). In an SMS method 810, the service provider sends a Short Message Service (SMS) message to a mobile telephone that needs an update (step 812). The information can be sent as 8-bit binary data. Because SMS messages are short, it is generally advantageous to send incremental updates rather than complete updates when possible. The update messages should have an otherwise-unlikely content so that the call rerouter can recognise that it is the intended recipient and prevent the messages from being displayed to the user. In one implementation, the SMS messages for the call rerouter include identifying 8-bit bytes of binary data at the beginning and end of each message including a data-dependent checksum, which should distinguish them from any messages intended to be displayed to the mobile telephone user.

For incremental updates of a rerouting information maintained in a table, the update command set can be as simple as commands to insert, delete, and overwrite table entries. The call rerouter parses the message and updates the routing table accordingly (step 814). The call rerouter optionally sends an acknowledgement in reply (step 816). Generally, the service provider will send the same SMS message to all subscribers to any particular service. If an acknowledgement is expected and the server does not receive any acknowledgement within a certain amount of time (generally, a period of days), the message is resent.

Using acknowledgements requires two SMS messages per subscriber for each change of the routing table, which can make the method costly if changes made often. The cost can be reduced by not sending an acknowledgement to the server. In that case, the server will know that the packet has not been received by some other means, such as by detecting use of superseded routing information, or by interacting with the call rerouter when it connects with a service provider switch or server. As an alternative to using SMS messages, the service provider can send cell broadcast messages to mobile telephones in one or more areas.

In a DCE method 820, the call rerouter and the service provider make a digital data connection to each other, such as a GSM digital channel connection, (step 822), and use this digital connection to exchange status and routing information (step 824).

In a modem method 830, the call rerouter makes a modem connection to the service provider through the analogue modem 1 18 (FIG. 1 ). Using this connection, status and routing data are exchanged (step 824). As an alternative to using a modem, the call rerouter and service provider can use a computer interface 1 10 (FIG. 1) to exchange information. The service provider can provide the information to a computer belonging to the subscriber B such as a personal computer receiving information from the service provider, whether over the Internet, on a diskette or CD-ROM, from a bulletin board service, or otherwise B and the call rerouter can obtain the information from the computer over a wire or wireless connection, as was described earlier.

As shown in FIG. 9, an update can be initiated (step 802) by a user, who can call a service provider server to update the programming of the accessory, which may include updating the routing table and updating other program components such as program modules stored on flash memory, for example (step 902). It may also be initiated by the service provider, if the service provider detects that the call rerouter is using out-of-date information, such as a superseded access number, for example (step 904). As a further alternative, the call rerouter can send version information - such as program and data module versions or checksums or both - to the service provider in a brief time window before the user's call is connected or after it is completed (step 906). On the basis of this information, the service provider determines whether an update is required (step 908), and if one is, it is initiated (step 802).

The invention can be implemented in digital electronic circuitry, or in microcontroller hardware, firmware, software, or in combinations of them. Apparatus of the invention can be implemented in a computer program product tangibly embodied in a machine-readable storage device for execution by a programmable processor; and method steps of the invention can be performed by a programmable processor executing a program of instructions to perform functions of the invention by operating on input data and generating output. The invention can be implemented advantageously in one or more executable program modules that are executable on a programmable system including at least one programmable instruction processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Each program can be implemented in a high-level procedural, declarative, or object-oriented programming language, in a special purpose virtual machine language or scripting language, in a processor assembly or machine language, or in any other language; and in any case, the language can be a compiled or interpreted language. Suitable processors include, by way of example, both general and special purpose microprocessors including microcontrollers. Generally, a processor will receive instructions and data from a read-only memory and/or a random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices and on-chip memory, such as EPROM, EEPROM, and flash memories. Any of the foregoing can be supplemented by, or incorporated in, an application-specific integrated circuits (ASIC).

The invention has been described in terms of particular embodiments. Other embodiments are within the scope of the following claims. For example, the steps of the invention can be performed in a different order and still achieve desirable results. Table-driven processes can be implemented as self-contained program modules. Aspects of the invention can be implemented within a mobile telephone or within a personality module, such as a SIM, configured to be inserted in the mobile telephone. Implemented in a SIM, the programming can interact with the mobile telephone using a SIM toolkit implemented in the mobile telephone.

More particularly, aspects of the invention can be implemented using facilities and interfaces of the Wireless Application Protocol (WAP), a standard defined and promulgated by the WAP Forum. The features of the WAP Wireless Telephony Application Interface (WTAI) provide a way to create telephony applications using a WTA user-agent with the appropriate WTAI function libraries, which give access to functions to control the mobile telephone. For example, to implement callback and access switch methods as a WAP application, the WAP application and the routing table are downloaded from the service provider. The application is cached in the telephone memory. When the user presses "Call", the following can occur:

1) The telephone looks up its current location through the WTAGSM. location function. This function returns, for example, the country code and area in which the telephone is located.

2) The telephone checks how to route the call by looking at its router table. 3a) If the access switch method is chosen, the access switch is called using the

WTA VoiceCall. setup function. At the same time an event-handler for Call Control / Call Connected is installed. 4a) When the event for Call Connected comes through the network, the desired phone number is sent with DTMF tones using the WTAVoiceCall.sendDTMF function. 3b) If the callback method is selected the CLI-server is called using the

WTAVoiceCall.setup function. At the same time an event-handler for Call Control / Incoming Call is installed.

4b) When the event for Incoming Call comes through the network a

WTA VoiceCall. release is made on the call to the CLI. 5b) The telephone uses a WTA VoiceCall. accept to answer the call from the callback server and then sends the desired number with WTAVoiceCall.sendDTMF.

The invention can be implemented in an add-on accessory that includes other functionality, such as a hands-free interface or a mobile telephone modem interface.

The routing data stored in a routing table can be stored in other data structures, such as a tree or a linked list structure, or it can be stored in program form, for example in a script or in a program of bytecode instructions for a simple virtual machine.

The routing data can simply be a prefix inserted before the destination number, in systems where a prefix can be used to select an alternative carrier.

Claims

CLAIMSWhat is claimed is:

1. An apparatus for providing telecommunications services to a subscriber having a mobile telephone, comprising: programming for the mobile telephone stored on a tangible medium of expression as digital electronic information comprising routing data and rerouting instructions, the programming being operable to change the operational behaviour of the mobile telephone in placing a telephone call requested by the subscriber, the programming being further operable to cause a telephone call requested by the subscriber to be rerouted to a subscriber-requested destination through a server connected to a public switched telephone network and wherein the programming is embodied in an add-on accessory.

2. The apparatus of claim 1, wherein: the programming includes instructions operable to receive updates to the routing data; and the programming is operable to use the routing data to determine whether and how to reroute the telephone call requested by the subscriber.

3. The apparatus of claim 2, wherein: the programming is operable to reroute the telephone call requested by the subscriber according to environment data provided by the mobile telephone.

4.. The apparatus of claim 1, wherein: the add-on accessory being configured to connect physically to the mobile telephone and to communicate with, and control operation of, the mobile telephone through an external interface on the mobile telephone.

5. The apparatus of claim 1, wherein; the add-on accessory being configured to be coupled to the mobile telephone with a wireless interface and to communicate with, and control operation of, the mobile telephone through the wireless interface.

6. The apparatus of claim 1, wherein the programming is embodied in a personality module configured to be inserted in the mobile telephone.

7. The apparatus of claim 6, wherein: the personality module is a Subscriber Identy Module (SIM); and the programming interacts with a mobile telephone using a SIM toolkit implemented in the mobile telephone.