HK1038134B - Multi-mode mobile terminal and methods for operating the same - Google Patents

Description

Multi-mode mobile terminal and method of operating multi-mode mobile terminal

Technical Field

The present invention relates to communication systems, and more particularly to a multi-mode mobile terminal operating in two or more wireless communication networks.

Background

Public cellular networks (public land mobile networks) are commonly used to provide voice and data communications to multiple users. Analog cellular radiotelephone systems, such as those known as AMPS, ETACS, NMT-450, and NMT-900, have been successfully employed worldwide. A digital cellular radiotelephone system, known for example as IS-S4B (and its successor IS-136), has recently emerged in north america, and GSM systems have been introduced throughout europe. These systems, and others, are described in a book entitled "cellular radio system" by BALSTON et al, published in 1993 by ARTECH HOUSE of ma. Satellite-based wireless communication systems, such as the asian cellular satellite system (ACeS) developed by Lockheed Martin, may also be employed to provide wireless communications in various regions. Furthermore, dual-mode terminals are known that can allow a single terminal to access different networks. For example, an analog/digital dual mode terminal or a terrestrial/satellite dual mode terminal may be adapted to various geographical areas so that the user may obtain the maximum communication capability.

Fig. 1 illustrates a conventional terrestrial wireless communication system 20 in which one of the above-described wireless communication standards may be implemented. The wireless system may include one or more wireless mobile terminals 22 in communication with a plurality of cells 24 served by base stations 26, and a Mobile Telephone Switching Office (MTSO) 28. Although only three cells 24 are shown in fig. 1, a typical cellular radiotelephone network may include hundreds of cells, and may also include more than one MTSO28, which may serve thousands of wireless mobile terminals 22.

In the communication system 20, the cells 24 generally serve as nodes through which a link may be established between the wireless mobile terminal 22 and the MTSO28 by way of the base station 26 serving the cell 24. Each cell 24 is assigned one or more dedicated control channels and one or more traffic channels. The control channel is a dedicated channel for transmitting cell identification and paging information. The traffic channels carry voice and data information. A duplex wireless communication link 30 may be established between two wireless mobile terminals 22 over the communication system 20, or between one wireless mobile terminal 22 and a landline telephone user 32 over a Public Switched Telephone Network (PSTN) 34. The function of the base station 26 is generally to handle wireless communications between the cell 24 and the wireless mobile terminal 22. In this capability, the base station 26 functions primarily as a relay station for data and voice signals.

Fig. 2 illustrates a conventional over-the-air wireless communication system 40. The over-the-air wireless communication system 40 may be employed to perform functions similar to those performed by the conventional terrestrial wireless communication system 20 shown in fig. 1. In particular, the over-the-air wireless communication system 40 typically includes one or more satellites 42 that may be used as relay services or as repeaters between one or more ground stations 44 and the satellite radioterminals 23. The satellite 42 communicates with the satellite radioterminals 23 and the ground station 44 over a duplex communications link 46. Each ground station 44 may, in turn, be connected to the PSTN34 to allow communication between the wireless mobile terminal 23 and the conventional land phone 32 (fig. 1).

The airborne wireless communication system 40 may utilize a single antenna beam to cover the entire area served by the system, or as shown in fig. 2, the airborne wireless communication system 40 may be designed to produce a plurality of beams 48 of minimal overlapping coverage, each beam serving a different geographic coverage area 50 within the system service area. The satellite 42 and the coverage area 50 function similarly to the base station 26 and the cell 24 of the terrestrial wireless communication system 20.

As such, the over-the-air wireless communication system 40 may be used to perform functions similar to conventional terrestrial wireless communication systems. In particular, the air-borne radiotelephone communication system 40 may be particularly useful in areas having a very wide geographic area and a sparsely populated area, or in areas where conventional ground-based telephony or ground-based radio infrastructure is not technically or economically feasible due to large terrain fluctuations.

Access control to various communication networks is typically provided by some form of user (subscriber) identification. In the earliest analog systems (e.g., AMPS systems), there was often no need to verify user identification, and charging for service was essentially based on the telephone number assigned to the analog mobile terminal. With the introduction of digital and satellite based systems, users (subscribers) of communication networks may have a wider choice of communication services, such as paging and short message services. These networks therefore typically require subscriber identity verification of a mobile terminal attempting to access the network at the level of subscriber identity authorization to the user. In a GSM system, for example, a Subscriber Identity Module (SIM) is typically provided to the mobile terminal, and the SIM provides a subscriber identity to be provided by the terminal to a communications network provider to gain access to the network. The network verifies that the provided identity is valid before allowing the mobile terminal access.

Access without a valid subscriber identity varies from communication network to communication network. For example, GSM allows emergency calls, while ACeS does not allow access. For normal operation, digital systems based on GSM typically require: when the mobile terminal is switched on, a SIM card with a valid subscriber identity is provided in the terminal. The subscriber identity may be verified by a network request during a network access procedure of the mobile terminal and may be granted or denied as a result of the procedure. When the authentication process fails, any SIM in the phone is typically considered invalid until the mobile terminal is turned off or the SIM card is replaced. If there is no valid SIM card available at power up, or if the SIM card is taken out or invalid, the system will typically only provide limited user services such as emergency calls. Without a valid SIM, no other system even provides emergency call access.

International publication number WO-A-9707642 describes A method and apparatus for accessing multiple networks. The subscriber identity module is associated with the terminal and the user is able to select an operation mode of the terminal in which the terminal will also maintain availability when the subscriber identity module is removed from the terminal. A wireless device capable of automatic system selection in an emergency situation is described in international publication number WO-A-9216077. The wireless device first transmits an emergency information signal in a first system and then transmits the emergency information signal in a second system after determining that the signal was not successfully transmitted in the first system.

Problems with dual mode mobile terminals arise when the subscriber identity is lost. The assigned identification is lost due to a failure to pay or other action by the user, or due to a communication error in the exchange of identification information with the communication network. The protocol of the mobile terminal for selecting the operation mode may not be optimal for user performance in case access to a network is affected.

Summary of The Invention

It is therefore an object of the present invention to address the problem of service selection agreements for multi-mode mobile terminals in situations where the subscriber identity has been determined to be invalid.

It is a further object of the present invention to provide a mobile terminal and method of operating the same that will attempt to provide emergency telephone service regardless of whether the mobile terminal has a valid subscriber identity.

These and other objects will be provided according to the present invention by: a multi-mode mobile terminal is provided with a subscriber identity which uses knowledge of the service level supported by the communications network to transition to a communications mode which allows the most possible services available when the subscriber identity is not valid. The mobile terminal of the present invention not only provides the ability to switch communication services from a current mode (network) to another mode to handle emergency calls, but also restricts user operation of the communication network based on available services that do not require a valid subscriber identity. The operation of the mobile terminal in the present invention may be supported by service level information in various communication networks, which may be stored in the memory of the mobile terminal or obtained by the mobile terminal from the network. Based on the service availability information for each communication network available to the mobile terminal, the mobile terminal may select an appropriate network for initiating a call when the mobile terminal does not have a valid subscriber identity. An example of such a call may be an emergency call such as a 911 call.

According to a first aspect of the present invention, there is provided, inter alia, a multi-mode mobile terminal with a subscriber identity. The mobile terminal comprises transceiver means for communicating in a first and a second wireless communication network. The terminal further comprises means for determining whether the first network allows no valid subscriber identity access and for determining whether the second network allows no valid subscriber identity access. In addition, the mobile terminal also comprises a device for judging whether the user identification of the mobile terminal is valid for the first network or the second network. Finally, the mobile terminal comprises means for controlling the transceiver means such that if the subscriber identity of the mobile terminal is not valid on both the first network and the second network, communication is made via a selected one of the first or second networks allowing access without a valid subscriber identity.

In another aspect of the mobile terminal of the present invention, the mobile terminal comprises display means for notifying the user that the user identification is invalid. The terminal further comprises input means for receiving input from a user specifying one of said first or second networks for communication. The means for controlling the transceiver in this embodiment further comprises means for controlling the transceiver means to communicate over one of the first or second networks as specified by the user.

The mobile terminal of the present invention can be used in the following environments: wherein the first network may be a satellite network and the second network may be a terrestrial network. The satellite network may be an asian cellular satellite system. Or the first network may be a digital network and the second network may be an analog network (e.g., AMPS network) that allows access to users without a valid satellite subscriber identity. The first network and the second network may both be terrestrial networks or they may both be satellite networks. The digital network may be an asian cellular satellite system. The digital network may also be a terrestrial network that only allows emergency call access without a valid subscriber identity. The means for controlling the transceiver comprises means for controlling the transceiver means so that when the AMPS network is one of the available networks, communication can be made over the AMPS network to provide the mobile terminal with the broadest available communication service without a valid subscriber identity.

In another embodiment of the present invention, the mobile terminal may include a subscriber identity module that contains a subscriber identity of the mobile terminal. The terminal may further comprise storage means containing definitions of available communication services available in the first and second networks without valid subscriber identities.

In another aspect of the mobile terminal of the present invention, the terminal includes means for inhibiting the transceiver means from operating in a communication mode in one of the first or second networks for which no active subscriber identity access is not permitted unless the mobile terminal has a valid subscriber identity for the one of the first or second networks for which no active subscriber identity access is not permitted. Or the terminal further comprises means for prohibiting user access to non-emergency communication services requiring a valid subscriber identity when the mobile terminal is communicating without a valid subscriber identity.

According to the method of the present invention, a method for dual mode operation of a mobile terminal in a first communication network allowing no active subscriber identity access and in a second communication network requiring active subscriber identity access is provided. The mobile terminal determines whether the user identification of the mobile terminal is valid. The mobile terminal then selects to operate in the first communication network when the subscriber identity is determined to be invalid. In one embodiment the selecting step comprises: when the subscriber identity is determined to be invalid, pre-stored network selection criteria are ignored and operation is automatically switched from the second communication network to the first communication network in response to a determination that the subscriber identity of the mobile terminal is invalid. In another aspect of the method of the present invention, a notification of an invalid subscriber identity may be provided to the subscriber and a confirmation of the subscriber to switch from the second communication network to the first communication network may be received prior to switching communication operations. The decision step may be initiated in response to a user initiated emergency call. When the subscriber identity is determined to be invalid, subscriber access to the communication service requiring a valid subscriber identity is prohibited.

The present invention thus provides an apparatus and method of operation that allows a multi-mode terminal to access a variety of communication networks that provide the best available communication services when the mobile terminal lacks a valid subscriber identity. The invention thus provides the highest level of available access and the opportunity to place important subscriber calls, such as emergency calls, even when the mobile terminal is not able to obtain a valid subscriber identity.

Brief Description of Drawings

FIG. 1 is a block diagram schematically illustrating a portion of a cellular network operating over a wide area, including a plurality of base stations serving different geographic regions;

FIG. 2 schematically illustrates a partial block diagram of a satellite-based cellular network operating over a wide area, including a plurality of spot beams covering different geographic areas;

FIG. 3 schematically illustrates an operating environment of the present invention in which one of the available networks is a satellite-based network and the other available networks are terrestrial networks;

fig. 4 is a block diagram illustrating a dual mode mobile terminal according to an embodiment of the present invention;

FIG. 5 is a flowchart illustrating operation of one embodiment of the present invention;

fig. 6 is a flow chart illustrating operation of another embodiment of the present invention.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. As will be appreciated by those skilled in the art, the present invention may be embodied as methods and apparatus. Thus, the present invention may take the form of a hardware embodiment, a software embodiment or a combination comprising both hardware and software aspects

Forms of embodiment appear.

Fig. 3 illustrates an operating environment of a dual mode mobile terminal according to the present invention. The satellite 42 projects a spot beam 48 toward a geographic area 50 to provide communication services from the first wireless communication network 40 to the user terminal 60. The frequency f used for the beam 48_eSystem information is broadcast on a control channel. The system information may include an identification of the communication network and other control information. The system information enables the user terminal to register with the system by identifying the beam of the service. Although only one spot beam is shown, the satellite may project multiple spot beams to provide service to multiple geographic areas, see FIG. 2.

The terrestrial communication base station 26 may be an integral part of the terrestrial cellular network 20, which may provide service to a portion of the geographic region 50. In particular, the cellular network may broadcast system information on a control channel, where the system information includes an identification of the communication network or other control information. The terrestrial communications network 20 may be, for example, an AMPS cellular radiotelephone system or a GSM cellular radiotelephone system. Although a specific example of a terrestrial communication system is given above, it should be understood that other systems providing analog information are within the scope of the present invention.

The operation of the present invention will be described herein primarily with reference to dual-mode mobile terminals operating in satellite systems (e.g., asian cellular satellite systems) as well as GSM or AMPS terrestrial systems. The advantages of the invention may also be realized by a mobile terminal operating in a digital terrestrial system (e.g., GSM1900) and AMPS. The present invention is also applicable to any type of multi-mode mobile terminal operating without a valid SIM in a system environment with different levels of system support services within different available communication networks. The invention is further described primarily with reference to a dual-mode mobile terminal that includes a subscriber identity module containing subscriber identity information, such as that known in the GSM digital terrestrial communications system. The advantages of the invention are however not limited to this type of terminal only, but can be embodied in any multimode terminal provided with means for associating a user identification with the mobile terminal.

Referring now to the embodiment illustrated in fig. 4, the user terminal 60 is a radiotelephone (e.g., a dual mode radiotelephone) capable of communicating with both the satellite communication system 40 and the terrestrial communication system 20. The user terminal 60 may operate as a satellite radiotelephone, or the user terminal 60 may switch between satellite and terrestrial modes under user control or automatically. The user terminal 60 includes an antenna 62 and a transceiver 64 or other transceiver device for transmitting and receiving information to and from a satellite network and/or a terrestrial network. Processor 66 receives information from and provides information to transceiver 64 and selects a channel for user terminal 60 to communicate with satellite communication network 40 or terrestrial network 20. The user terminal memory 68 stores information related to the satellite communication network 40 and the terrestrial communication network 20. The user interface 70 may include a keypad for a user to control the operation of the user terminal 60. The subscriber terminal 60 may also include a Subscriber Identity Module (SIM)72 containing a subscriber identity which is used to control access to the satellite communications network 40 and/or the terrestrial communications network 20.

In accordance with the present invention, processor 66 performs operations in accordance with the present invention for which there is no valid SIM. The processor 66 provides means for determining whether a first network available to the mobile terminal allows no valid subscriber identity access (or available service level) and provides means for determining whether a second network available to the mobile terminal allows access with a valid subscriber identity (or available service level). As described above, this means may be provided by processor 66 by accessing communication network service level information pre-stored in memory 68 or otherwise obtained by processor 66 through communication with the first and second networks. In a simple case, the second network may be a satellite network that does not allow access (e.g., ACeS), while the first network may be a terrestrial network that possesses some level of access, and the decision operation may simply require a biasing of the mobile terminal to select the terrestrial network described herein for operation without a valid SIM.

As further shown in fig. 4, processor 66 is also connected to SIM 72 and provides a means for determining whether the subscriber identity from SIM 72 is valid for the first network or the second network. The processor 66 also provides means for controlling the transceiver 64 so that if the subscriber identity of the mobile terminal 60 is not valid in the first and second networks, it can also communicate in a selected one of the first or second networks that allows access without a valid subscriber identity.

If the subscriber identity is valid in the first or second network, the operation preferably continues in the network where the valid identity is present, as it is generally desirable to provide a higher level of service. It is an object of the present invention to provide the highest level of available services.

The user interface 70 provides input and output means. According to one embodiment of the invention, the interface 70 includes a display device for notifying the user that its user identification has been invalidated. The interface 70 also includes an input device (e.g., a keypad) for receiving input from a user to specify which of the first or second networks is to be used for communication. In this embodiment, the processor 66 includes means for controlling the transceiver 64 to communicate over one of the first or second networks as specified by the user. The memory 68 preferably contains definitions of the available communication service levels in the first and second networks in the absence of a valid subscriber identity.

In the embodiment shown in fig. 4, the processor 66 further comprises means for disabling the transceiver 64 from communicating over one of the first network or the second network that is not allowed to have access without a valid subscriber identity unless the mobile subscriber terminal 60 possesses a valid subscriber identity for one of the first network or the second network that is not allowed to have access without a valid subscriber identity. Or the processor 66 may comprise means for prohibiting the user from accessing communication services requiring a valid subscriber identity in the communication network when the mobile terminal is communicating without a valid subscriber identity. Thus, the mobile terminal 60 may continue to allow the user access to certain services in the communication network, but may not access other services, when no valid subscriber identity is available.

Those skilled in the art will appreciate that the various aspects of the present invention described above in fig. 4 may be provided by hardware, software, or a combination of both. Although the various components within the mobile terminal 60 are shown in fig. 4 as part of a discrete unit, in practice they may be implemented by a microcontroller containing input and output ports and running software code, or by custom or hybrid chips, or by discrete components, or by a combination of the above. For example, the memory 68 may be contained within the processor 66.

The operation of the present invention may also be described with reference to fig. 5 and 6. It will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by computer program instructions. These program instructions may be provided to a processor to produce a machine, such that the instructions, which execute on the processor, create means for implementing the functions specified in the flowchart block or blocks. The computer program instructions may be executed by a processor to cause a series of operational steps to be performed by the processor to produce a computer implemented process such that the instructions, which execute on the processor, provide steps for implementing the functions specified in the flowchart block or blocks.

Accordingly, blocks of the flowchart illustrations support combinations of means for performing the specified functions, and combinations of steps for performing the specified functions and program instruction means for performing the specified functions. It will also be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by special purpose hardware-based systems which perform the specified functions or steps, or by combinations of special purpose hardware and computer instructions.

Referring now to fig. 5, operations begin at block 80 when the processor 66 determines whether the mobile terminal 60 has a valid subscriber identity. The check may be initiated at power-up or in response to a request by the mobile terminal user to initiate a call, such as an emergency call. In block 82, when the subscriber identity is determined to be invalid, processor 66 ignores any pre-stored network selection criteria. In block 84, the mobile terminal user is notified that an invalid subscriber identity exists within the mobile terminal. The mobile terminal 60 receives a user confirmation of the handover from the second communication network to the first communication network, block 86. When it is determined that the subscriber identity of the mobile terminal is not valid, the operation is handed over from the second communication network to the first communication network, block 88.

For the purposes of the description herein, the first communication network allows at least a variety of accesses without a valid subscriber identity, while the second communication network requires that any type of access must be provided with a valid subscriber identity. It will be appreciated, however, that even if a limited form of access without a valid subscriber identity is available in the second communication network, or some access without a valid subscriber identity is not allowed in the first communication network, it is preferred to prefer the first communication network over the second communication network operating in accordance with the present invention. According to the method of the present invention, the first communication network is preferred over the second communication network because the first communication network may provide a higher level of access to the user without a valid user identification, or because subscription data is employed in the first communication network that is independent of data used in the second communication network.

Although in the operational embodiment described with reference to fig. 5 the notification and confirmation of the handover is provided to and by the user, this is not essential to obtain the advantages of the present invention. Alternatively, the operation of switching the mode of the communication network may be initiated automatically in block 88 in response to the determination of an invalid ID in block 80. And additional operations may be provided in block 88 to control the user attempting access to the communications network without the mobile terminal 60 having a valid subscriber identity. In block 88 of this embodiment, after the communication network mode is switched, the mobile terminal 60 prohibits user access to communication services within the second communication network requiring a valid subscriber identity and for which the subscriber identity of the mobile terminal is determined to be invalid. Furthermore, any communication services requiring a valid subscriber identity in the first communication network will also prevent access to the mobile terminal 60 by those users who do not have a valid subscriber identity in the mobile terminal.

The operation of a particular embodiment of the present invention will now be described in more detail with reference to fig. 6. For the purposes of describing fig. 6, the first communication network (i.e., the network allowing a higher level of service without a valid subscriber identity module) is a terrestrial communication network, while the second communication network (the lower level of service) is a satellite network. The operations in the flow chart of fig. 6 begin with the mobile terminal 60 being powered on in the satellite mode. According to the flow chart in fig. 6, the operation is intended to be able to provide the best possible service to the user of the mobile terminal in a secure and user-friendly manner, i.e. at least a limited service in terrestrial mode.

In block 100, the mobile terminal 60 checks to see if it has a valid SIM card when it is powered up. In a mobile terminal using a SIM card, this is judged by checking the physical presence of a valid SIM card. When no valid SIM card is available, the limited available service in the terrestrial mode is provided with a higher priority than the unavailable service in the satellite mode. For the purposes of this description, it is assumed that the satellite communications network is a network such as the asian cellular satellite system that does not provide services for terminals without a valid subscriber identity.

If no valid SIM card is detected in block 100, operation may transition to block 102 and an indication of no valid subscriber identity may be provided to the mobile terminal user. The user is also prompted to switch to terrestrial mode at block 102. User communications may be performed through the mobile terminal user interface 70 and may involve the display of text or images, audio signals, or other input-output devices.

Upon receiving user confirmation of the proposed switch to terrestrial mode at block 102, the mobile terminal ignores any pre-stored information that prioritizes or restricts use of the terrestrial system at block 104 and attempts to establish a communication link in the terrestrial channel to allow the user-initiated emergency call. Alternatively, block 102 may be skipped and block 104 awaited user confirmation may be skipped and the mobile terminal 60 may automatically initiate operation to switch to terrestrial mode.

If a valid SIM card is detected at power up in block 100, the mobile terminal 60 continues to operate in the satellite mode in block 106. However, the mobile terminal 60 may also view the active SIM at various times other than during power-up. If during the review the mobile terminal 60 determines that the valid subscriber identity is no longer valid (as in block 108) due to the SIM card being removed, operation transfers to block 102 to initiate the transition operation to ground mode. Furthermore, as shown in block 110, upon non-emergency network access for satellite mode operation, instances of invalid user identification may be encountered due to, for example, a failed verification of the user or mobile device identification in response to a service request, location update, authentication check, or the like. Apart from the reason for taking the card away, other possible reasons for losing a valid subscriber identity in connection with the network include illegal operations, etc. If the SIM is not active when non-emergency network access is identified in block 110, operation again jumps to block 102 to switch to terrestrial mode operation.

Finally, an emergency call from a user request in satellite mode operation (as shown in block 112) initiates a check for the presence of a valid subscriber identity in block 114. If a valid subscriber identity is detected at block 114, the emergency call is processed in satellite mode as indicated at block 116. If the SIM is determined to be invalid in block 114, the emergency call is processed in a terrestrial mode in block 118.

As shown in the embodiment of fig. 6, emergency calls can be handled immediately in terrestrial mode without waiting for a handoff confirmation from the user. This is the preferred method of operation since it provides the fastest possible terrestrial mode network access to initiate emergency calls. The operations in block 118, however, may provide an indication to the user that no valid user identification exists and request confirmation from the user to switch to ground mode before initiating the emergency call.

At block 120, the mobile terminal 60 has successfully switched from satellite to terrestrial mode operation. When operating in a terrestrial mode without a valid subscriber identity, the mobile terminal ignores any pre-stored information used to control the satellite mode as opposed to the terrestrial mode. The mobile terminal preferably does not attempt to transition to satellite mode operation due to any event in idle mode terrestrial operation, such as a reselection initiated by the operator. However, the operation of the user of the mobile terminal will be provided in accordance with the description to be made.

When the mobile terminal 60 receives a network mode selection request to transition to satellite mode, as shown in blocks 120 and 122, the request is checked to determine if it was initiated by the mobile terminal user in block 122. If so, the request is processed in block 124 and the mobile terminal 60 attempts to reestablish satellite mode operation. If, however, it is determined at block 122 that the request is not from the user of the mobile terminal, then at block 126 the request is denied and operation continues in terrestrial mode.

Although not shown in fig. 6, if the SIM card is replaced and a valid subscriber identity exists, the mobile terminal resumes normal operation, including using any pre-stored system priority or restriction information, and based on such system priority information, the mobile terminal may switch back to the satellite mode of operation. And although terrestrial mode operation is a result of a lack of a valid subscriber identity, the user interface functionality of the mobile terminal is preferably limited to areas that require interoperation with the subscriber identity in order to be performed. Subscriber services, menus and selection operations that the SIM card is required to support may thus be disabled by the mobile terminal 60. Such disabling may be accomplished by making the corresponding portions of the user interface unavailable to the user, for example, by not placing the portions on the display or marking them in a manner that can distinguish them from the available user functionality. The mobile terminal 60 may then ignore those relevant user actions that request non-available services. As discussed in block 102, the user is provided with an indication of a continuous invalid user identification throughout terrestrial mode operation.

In land mode operation, if an emergency call request is received from a user as shown in block 128, the request is processed in block 130 and the emergency call is placed in the land network.

In the case where the terrestrial network allows access to subscribers without a valid subscriber identity other than the emergency call, the processing of the non-emergency call request may be performed as indicated in block 130 and 136. These operations provide the user with a medium level of access in a network environment where if the interworking of the communication network has been disabled in one part of the system independent subscription, it can no longer be disabled in at least another part. An example of such an application is a multi-mode phone for asian cellular satellite systems that use AMPS as a terrestrial mode service. Such an application may also be used for ground-based digital dual-mode phones that have access to a digital GSM network and an analog AMPS network, where supplementary services other than emergency calls may be provided within the AMPS network. In this case, terrestrial mode should be understood to mean AMPS mode, or other service that provides a user with no active non-AMPS mode user identification access beyond an emergency call.

Referring again to fig. 6, after receiving a non-emergency call request in terrestrial mode in block 130, the mobile terminal 60 determines whether subscription access exists based on a non-subscriber identity module in terrestrial mode in block 132. If such access exists, in other words, if it is determined in block 132 that non-emergency access is available, then the call request is processed in terrestrial mode in block 136. If, however, no non-emergency access is available at block 132, the request is denied as shown at block 134.

Although the invention has been described above in relation to handover in two networks, it will be appreciated by those skilled in the art that the invention is also applicable to a greater number of networks. In this case, a hierarchical network selection may be established in order to provide the highest level of available access based on the available networks. And the ranking may be dynamically determined by the processor 60 based on the available networks.

As described above, the multi-mode mobile terminal and method of operating in multiple modes of the present invention can provide the highest level of available services for operation of the mobile terminal within a complex multi-mode telephone system environment in which different levels of non-subscriber identity access of the mobile terminal are supported by different communication networks. This capability is provided in a secure and user-friendly manner, which is more advantageous in emergency call situations. The described operations typically require reliability and are consistent with the requirements of the prior art specifications for terrestrial and satellite networks that are currently known. The apparatus and method of the present invention can be easily implemented and applied to mobile terminal devices employing a variety of subscriber identity configurations.

In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.

Claims (22)

1. A multimode mobile terminal (60) with a subscriber identity and with transceiver means (64) for communicating in a first and a second wireless communication network, characterized in that the terminal further comprises:

means for determining whether the first network allows access without a valid subscriber identity;

means for determining whether the second network allows access without a valid subscriber identity;

means for determining whether the subscriber identity is valid for the first network;

means for determining whether the subscriber identity is valid for the second network;

means for controlling the transceiver means such that if the subscriber identity of the mobile terminal is not valid in both the first and second networks, communication is made via a selected one of the first or second networks which allows access without a valid subscriber identity.

2. The mobile terminal of claim 1 further comprising:

display means for notifying a user that the user identification is invalid;

input means for receiving an input from a user specifying one of the first or second networks to be used for communication; and

wherein said means for controlling comprises means for controlling transceiver means to communicate over one of said first or second networks as specified by a user.

3. The mobile terminal of claim 1, wherein said first network is a satellite network and said second network is a terrestrial network.

4. The mobile terminal of claim 3, wherein said satellite network is an Asian cellular satellite system.

5. The mobile terminal of claim 1 wherein said first network is a digital network and said second network is an AMPS network that allows access without a valid subscriber identity.

6. The mobile terminal of claim 5, wherein said digital network is an Asian cellular satellite system.

7. The mobile terminal of claim 5, wherein said digital network is a terrestrial network that only allows emergency call access in the absence of a valid subscriber identity.

8. The mobile terminal of claim 7 wherein said means for controlling includes means for controlling transceiver means that enable communication over said AMPS network to provide the mobile terminal with the broadest available communication service without a valid subscriber identity.

9. The mobile terminal of claim 1, further comprising a subscriber identity module (72) including a subscriber identity of the mobile terminal for at least one of the first and second networks.

10. The mobile terminal of claim 9, further comprising a memory device (68) containing a definition of available communication services available from the first and second networks without valid subscriber identities.

11. The mobile terminal of claim 1, further comprising means for inhibiting the transceiver from operating in a communication in one of the first network or the second network that is not allowed access without a valid subscriber identity unless the mobile terminal has a valid subscriber identity for the one of the first network or the second network that is not allowed access without a valid subscriber identity.

12. The mobile terminal of claim 1, further comprising means for inhibiting a user from accessing a communication service requiring a valid subscriber identity when the mobile terminal is communicating without a valid subscriber identity.

13. The mobile terminal of claim 1 wherein the means for controlling the transceiver means further comprises: means responsive to the means for determining whether the first network allows access and the means for determining whether the second network allows access, for controlling the transceiver means to communicate in a selected one of the first or second networks that allows access without a valid subscriber identity if the subscriber identity of the mobile terminal is not valid in both the first network and the second network.

14. A method for selecting a network for a dual mode mobile terminal (60) in a first communication network allowing a first level of access without a valid subscriber identity and in a second communication network allowing a second level of access lower than the first level of access without a valid subscriber identity, said mobile terminal (60) having a subscriber identity, the method comprising the steps of:

judging a first level access and a second level access;

judging whether the user identification of the mobile terminal (60) is valid; and

and when the user identification is judged to be invalid for the second communication network, selecting to operate in the first communication network.

15. The method of claim 14 wherein the step of selecting operation within the first communication network when the subscriber identity is determined to be invalid for the second communication network further comprises: and automatically selecting the step of operating within the first communication network when the subscriber identity is determined to be invalid for the second communication network.

16. The method of claim 14, wherein said selecting step comprises the steps of:

when the user identification is judged to be invalid, ignoring a pre-stored network selection standard; and

when the user identification of the mobile terminal (60) is invalid, the operation is automatically switched from the second communication network to the first communication network on the basis of the judgment of the first level and the second level.

17. The method of claim 14, wherein said selecting step comprises the steps of:

providing a notification to the user of an invalid user identification; and

a user confirmation of a handover from the second communication network to the first communication network is received.

18. The method of claim 14, wherein the step of determining whether the subscriber identity of the mobile terminal (60) is valid is initiated in response to a subscriber initiating operation in at least one of the first communication network or the second communication network.

19. The method of claim 14, wherein the step of determining whether the subscriber identity of the mobile terminal (60) is valid is initiated as part of a system access attempt initiated by at least one of the subscriber or the mobile terminal.

20. The method of claim 14, wherein the step of determining whether the subscriber identity of the mobile terminal (60) is valid is initiated in response to a subscriber-initiated emergency call.

21. The method of claim 14, further comprising the step of ignoring pre-stored network selection criteria when the subscriber identity is determined to be invalid.

22. The method of claim 14, further comprising the step of prohibiting user access to communication services requiring a valid subscriber identity when the subscriber identity is determined to be invalid.