Patent Publication Number: US-6658253-B1

Title: Method of providing services to a mobile station in visited networks

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a divisional of application Ser. No. 08/680,225, filed Jul. 11, 1996, now U.S. Pat. No. 6,073,015 for which notice of allowance has been issued. 
    
    
     The present invention relates generally to mobility management of a mobile subscriber unit operable in a microcellular communication network, such as a Digital Electronic Cordless Telephone (DECT) system or other Private Telephone Network (PTN). More particularly, the present invention relates to a method, and associated apparatus, for facilitating communications to and from the mobile subscriber unit pursuant to the microcellular communication network when the mobile subscriber unit roams into an area encompassed by a communication network other than the “home” microcellular communication network in which the mobile subscriber unit is regularly registered. 
     The microcellular communication networks are interfaced with a macrocellular communication network, such as a Global System for Mobile communications (GSM) or other Public Land Mobile Network (PLMN). Wide-area, mobility management functions existent in the macrocellular communication network are utilized by the microcellular communication network to provide wide-area mobility management to the microcellular communication network. Wide-area mobility of the mobile subscriber unit is permitted as the wide-area mobility management functions of the macrocellular communication network are used to facilitate the communication with the mobile subscriber unit. When the mobile subscriber unit roams beyond an area encompassed by the microcellular communication network in which the mobile subscriber unit is regularly registered, calls can still be routed to and from the mobile subscriber unit. 
     When the macrocellular communication network is formed of a GSM network, a mobility server positioned in the microcellular communication network is coupled to the GSM network and appears to the GSM network as a mobile services switching center (MSC) thereof. The wide-area, mobility management functions are used by the mobility servers of both the subscriber unit&#39;s “home” network and the “visited” network into which the subscriber unit roams thereby to provide wide-area mobility to the mobile subscriber unit. 
     Communications between the microcellular and macrocellular communication networks are also permitted to be effectuated by way of the Internet. Data to be communicated between the networks is encapsulated according to-an Internet protocol, or the like. 
     BACKGROUND OF THE INVENTION 
     Advancements in the fields of electronics and communications have permitted the introduction and commercialization of many new types of communication systems. Information can be affordably communicated to locations and in manners previously not possible or affordable. 
     The field of cellular telephony is exemplary of a communication system that has been made possible due to such advancements. A fixed, wireline connection is not required between a transmitting station and a receiving station in a cellular, or other radiotelephonic, communication system to effectuate communications between the stations. Because a “wireless” connection is formed between the transmitting station and the receiving station, use of such a communication system is particularly advantageous to effectuate communications when a wireline connection cannot be conveniently or practically formed. 
     Various different types of cellular, and other radiotelephonic, communication systems have been implemented and others have been proposed. In many parts of the world, for instance, macrocellular communication networks have been installed. Such networks permit mobile subscriber units positioned anywhere within the area encompassed by the macrocellular networks to communicate pursuant to the macrocellular communication network. A macrocellular communication network typically includes a large number of base stations positioned at spaced-apart locations throughout a geographic area. As a mobile subscriber unit moves throughout the geographical area, communications with the mobile subscriber unit are “handed-off” to successive ones of the base stations. In one type of cellular communication system, a Global System for Mobile (GSM) communications system, control circuitry, including mobile services switching centers (MSCs) and base stations controllers (BSCs), controls communications between the base stations and the mobile subscriber unit. And, location registers, including a home location register (HLR) associated with the mobile subscriber unit, maintain a registry of the positioning of the mobile subscriber unit in a network. 
     Microcellular communication networks have also been developed and implemented. A Digital Electronic Cordless Telephone (DECT) system is exemplary of a microcellular communication network. A microcellular communication network, analogous to a macrocellular communication network, also permits wireless communications to be effectuated with a mobile subscriber unit. The area encompassed by a microcellular communication network is, however, typically much smaller than the area encompassed by a macrocellular communication-network. 
     The costs associated with a microcellular communication network are generally less than the costs associated with a macrocellular communication network. However, because microcellular communication networks generally encompass limited areas, a single business, or other operator, might be required to construct more than one microcellular communication network to encompass a desired area in which microcellular communications are to be permitted. 
     For instance, a microcellular communication network might be constructed to provide microcellular communication coverage encompassing a single building. A mobile subscriber unit regularly registered to communicate pursuant to the microcellular communication network must be within the building, i.e., the area encompassed by the microcellular communication network, to communicate therethrough. 
     It is sometimes desirable to permit a mobile subscriber unit, regularly registered in one microcellular communication network (the “home” network), also to communicate in another microcellular communication network (the “visited” network). For instance, a business might have separate office locations, requiring separate microcellular networks to be installed for each of the separate office locations. It is sometimes desirable, in such instances, to permit personnel regularly located at one of the office locations to be able to communicate by way of a microcellular communication network even when the personnel are temporarily positioned at the other one of the office locations. 
     By providing communication links between the separate microcellular networks, registration, and other, information pertaining to the mobile subscriber unit stored at the “home” microcellular communication network can be used to permit communications with the mobile subscriber unit, even when the mobile subscriber unit is positioned in an area encompassed by the “visited” microcellular communication network. 
     Various proposals have been set forth to form communication links between microcellular networks by way of a macrocellular communication network. Such proposals, however, have generally been set forth for purposes of call control and not for purposes of mobility management. Viz. existing proposals for intercoupling the networks have not generally pertained to providing wide-area mobility to mobile subscriber units of microcellular communication networks. 
     Additionally, existing proposals generally require direct connections between the microcellular and macrocellular communication networks. As the operators of the macrocellular and microcellular communication networks might well be different entities, the conventional requirement for direct connections between the microcellular communication networks might sometimes be problematical. 
     A manner by which better to provide wide-area mobility to a mobile subscriber unit to increase the mobility permitted of the mobile subscriber unit would be advantageous. 
     Additionally, a manner by which to provide for the communication of mobility management information between a microcellular and macrocellular communication network without requiring direct connections therebetween would also be advantageous. 
     It is in light of this background information related to mobility management in a cellular communication system that the significant improvements of the present invention have evolved. 
     SUMMARY OF THE INVENTION 
     The present invention advantageously provides a method, and associated apparatus, for facilitating communications to and from a mobile subscriber unit operable in a microcellular communication network when the mobile subscriber unit roams into an area encompassed by a “visited” microcellular communication network other than the “home” network in which the mobile subscriber unit is regularly registered. 
     Wide-area mobility management functions available in a macrocellular network are provided to microcellular networks by coupling the microcellular networks to the macrocellular network. Wide-area mobility is thereby provided to a mobile subscriber unit operable in a microcellular communication network. The wide-area management functions provided to the microcellular communication network permits a mobile subscriber unit to communicate by way of a microcellular communication network even when it roams into an area encompassed by a “visited” network. 
     When the macrocellular communication network is formed of a Global System for Mobile communications (GSM) network, the microcellular communication networks include the mobility servers which appear, to the GSM network, to be mobile services switching centers (MSCs) of the GSM network. Mobility management normally provided to the mobile services switching centers of the GSM network are provided to the mobility servers of the microcellular networks. Signaling between the mobility server and the macrocellular communication network permits, for example, calls to be placed to and from a mobile subscriber unit when the subscriber unit roams beyond the microcellular communication network in which the subscriber unit is regularly registered. Location updating of the position at which the subscriber unit roams is similarly also effectuated. 
     In one aspect of the present invention, location information related to the position of a mobile subscriber unit is updated when the mobile subscriber unit roams into an area encompassed by a microcellular communication network other than the network in which the subscriber unit is regularly registered. A mobility server of such “visited” microcellular network receives indications of the positioning of the subscriber unit and provides information indicative thereof to a home location register (HLR) of the macrocellular communication network. The home location register (HLR) provides the visited mobility server with subscriber data related to the mobile subscriber unit and orders the “home” mobility server of the subscriber unit&#39;s home network to deregister the subscriber unit therefrom. 
     In an another aspect of the present invention, calls originated at a Public Switched Telephone Network (PSTN) to be terminated to a mobile subscriber unit of the “home” microcellular communication network are routed to the subscriber unit when the subscriber unit roams beyond the “home” network and into a “visited” network. In one exemplary routing method, the call is routed via the home microcellular communication network to a gateway mobile services switching center (GMSC) of the macrocellular communication network, and the GMSC interrogates the home location register of the macrocellular network to obtain routing information to route the call to the roaming, subscriber unit. The HLR requests and receives information from the mobility server of the “roaming” microcellular network. Such information is provided to the GMSC, and the call is routed to the mobile subscriber unit, to be terminated thereat. 
     In another aspect of the present invention, a call originated at a roaming, subscriber unit is routed to a subscriber, unit registered in the macrocellular communication network. And, in yet another aspect of the present invention, calls are placed between a mobile subscriber unit positioned in a “home” microcellular network to a mobile subscriber unit roaming in a “visited” microcellular communication network. And, in yet another aspect of the present invention, the mobile subscriber unit forms a dual-mode subscriber unit, operable in both a microcellular network and a macrocellular network. Calls are placed, or received, by the subscriber unit when the subscriber unit is positioned in its “home” microcellular network, a visited microcellular network, or within an area encompassed only by the macrocellular network. 
     The present invention further advantageously permits communications between the microcellular and macrocellular communication networks by way of an Internet communication channel. Mobility management information, for example, is encapsulated according to an Internet protocol, or the like, and thereafter communicated by way of the Internet forming a connection between the microcellular and macrocellular communication networks. Because communications between the microcellular and macrocellular communication networks are effectuated by way of the Internet, direct connections between the separate networks are not required. The Internet, already existent and readily accessible, can thereby be utilized both to facilitate data communications and also telephony communications. 
     In these and other aspects, therefore, mobility-enhancing apparatus for a first mobility server facilitates communication with a mobile subscriber unit. The mobile subscriber unit is operable in a first microcellular communication network of a communication system having a macrocellular communication network and at least the first microcellular communication network. The first microcellular communication network includes the first mobility server. The mobility-enhancing apparatus facilitates communication with the mobile subscriber unit, operable in the first microcellular communication network, in a communication network other than the first microcellular communication network. A storage device stores location information representative of positioning of the mobile subscriber unit. A mobility manager is coupled to the storage device and to the macrocellular network. The mobility manager at least updates the location information stored in the storage device to indicate whether the mobile subscriber unit is positioned within range of the first microcellular communication network. The mobility manager further receives macrocellular network-generated data related to the mobile subscriber unit, and the network-generated data is used for the updating of the location information. 
    
    
     A more complete appreciation of the present invention and the scope thereof can be obtained from the accompanying drawings which are briefly summarized below, the following detailed description of the presently-preferred embodiments of the invention, and the appended claims. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a functional block diagram of a communication system which includes an embodiment of the present invention as a portion thereof. 
     FIG. 2 illustrates a functional block diagram of a portion of the communication system shown in FIG. 1 used during operation of an embodiment of the present invention to update the location of a mobile subscriber unit when the mobile subscriber unit roams into an area encompassed by a microcellular communication network other than the “home” microcellular network in which the subscriber unit is regularly registered. 
     FIG. 3 illustrates a functional block diagram of a portion of the communication system shown in FIG. 1 used during operation of an embodiment of the present invention when the mobile subscriber unit roams into an area encompassed by a microcellular communication network other than the “home” network in which the subscriber unit is regularly registered. 
     FIG. 4 illustrates a portion of the communication system shown in FIG. 1, used during operation of an embodiment of the present invention to route a call originated by a mobile subscriber unit when the mobile subscriber unit is positioned in an area encompassed by a microcellular communication network other than the “home” network in which the subscriber unit is regularly registered. 
     FIG. 5 illustrates a portion of the communication system shown in FIG. 1 used during operation of an embodiment of the present invention to route a call between subscriber units positioned in different microcellular communication networks. 
     FIG. 6 illustrates a functional block diagram of a communication system which includes another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring first to FIG. 1, a communication system, shown generally at  10 , includes an embodiment of the present invention as a portion thereof. The communication system  10  is a multi-network communication system, here shown to include a macrocellular communication network  12 , a first microcellular communication network  14 , and a second microcellular communication network  16 . 
     The microcellular communication network  12 , for purposes of illustration, in the exemplary embodiment, is formed of a Global Systems for Mobile communications (GSM) network. In other embodiments, the macrocellular communication network  12  is alternatively formed of another type of Public Land Mobile Network (PLMN) Analogously, the first and second microcellular communication networks  14  and  16 , respectively, are, in the exemplary embodiment, formed of Digital Electronic Cordless Telephone (DECT) systems. The microcellular networks  14  and  16  shall, at times, be referred to as DECT systems. In another embodiment, the networks  14  and  16  are alternatively formed of other types of Private Telephonic Networks (PTNs). 
     The macrocellular, communication network  12  encompasses a macrocellular-region throughout which wireless communications by way of the network  12  are permitted. In conventional manner, the network  12  includes a plurality of spaced-apart base stations, of which two base stations  18  are illustrated in the figure. Each base station  18  encompasses an area defining a cell  20 . The cells  20  defined by the base stations  18  collectively form the region encompassed by the network  12 . 
     The base stations are coupled by way of base station controllers  22  to mobile services switching centers (MSCs), such as the mobile services switching centers  24  and  26 . The base station controllers  22  are operable, inter alia, to control operation of the base stations  18  coupled thereto. Control operations, such as hand-off decisions and channel allocations, are performed at the controllers  22 . Operation of the base station controllers  22 , and the mobile services switching centers  24  and  26  of the exemplary embodiment corresponds generally with operation of such devices in existing standards specifications. 
     The mobile services switching centers  24  and  26  shown in the figure are inter-coupled, here indicated by the lines  28 . The MSCs  24  and  26  are further coupled to a Public Switched Telephone Network (PSTN). Such couplings are illustrated by lines  32  and  34 , respectively, in the figure. 
     The GSM network  12  further includes location registers including the home location register (HLR)  36 . The HLR  36  is coupled to the MSCs  24  and  26  by way of lines  38  and  42 , respectively. The HLR  36  is operable in the GSM communication network  12 , inter alia, to perform wide-area mobility management functions to facilitate call routing to and from mobile subscriber units operable to communicate by way of the communication network  12 . Such mobility management functions include, for instances the maintenance of a subscriber registry. The subscriber registry contains information relating to the subscriber units&#39; whereabouts and status. 
     The HLR  36  is further coupled, by way of lines  44  and  46 , respectively, to mobility servers  48  and  52  of the DECT systems  14  and  16 , respectively. In an exemplary embodiment, the mobility servers  48  and  52  are based on MD  110  hardware components. Services supported therefrom are developed on an Erlang platform. Services performed by the mobility servers  48  and  52  include those which are conventionally provided by mobility servers of conventional DECT systems. 
     The mobility server  48  is coupled to radio exchange equipment  54  by way of lines  56 . The radio exchange equipment  54  includes transceiver circuitry permitting communication with mobile subscriber units, such as the mobile subscriber unit  58 . Similarly, the mobility server  52  is coupled to radio exchange equipment  62  by way of lines  64 . Analogous to the radio exchange equipment  54 , the radio exchange equipment  62  includes transceiver circuitry permitting wireless communications with mobile subscriber units positioned within the area encompassed by the DECT system  16 . 
     In one embodiment, the mobile subscriber unit  58  forms a dual-mode subscriber unit, selectively operable to communicate with both the GSM network  12  and the microcellular networks  14  and  16 . 
     The mobility server  48  includes a mobility manager  66  capable of communicating information with the HLR  36 . The mobility manager  66  is further coupled to a storage device  68  which also forms a portion of the mobility server  48 . Similarly, the mobility server  52  includes a mobility manager  72  which is capable of communicating information with the HLR  36 . The mobility manager is further coupled to a storage device  74  which also forms a portion of the mobility server  52 . The mobility server  48  is further coupled to the MSC  24 , here indicated-by lines  76 . And, the mobility server  52  is further coupled to the MSC  26 , here indicated by the lines  78 . Both the mobility servers  48  and  52  are further coupled to a PSTN and provide conventional call routing of calls between the PSTN and mobile subscriber units which are regularly registered in the respective communication networks  14  and  16 . 
     The storage devices  68  and  74  store location information related to subscriber units operable in the respective networks associated with the mobility servers  48  and  52 , respectively. As shall be described below, such location information can be updated during operation of an embodiment of the present invention. In one embodiment, the storage devices  68  and  74  further store service subscription information related to service subscriptions to which the subscriber units are subscribed. 
     During operation of an embodiment of the present invention, the wide-area mobility management functions provided by the GSM network  12  are further utilized by the DECT systems forming the microcellular networks  14  and  16 . Such utilization provides wide-area mobility to mobile subscriber units operable in the networks  14  and  16 . Thereby, communications with mobile subscriber units of the networks  14  and  16  are permitted when such subscriber units roam beyond the areas encompassed by the networks in which the subscriber units are regularly registered, viz., the subscriber units “home” network. For instance, when the mobile subscriber unit  58  roams beyond the microcellular network  14  and into, for instance, the microcellular network  16 , the wide-area mobility management functions provided by the GSM network  12  are utilized to facilitate communications with the “roaming” mobile subscriber unit. In an embodiment having dual-mode subscriber units, the wide-area mobility management functions provided by the GSM network are utilized by the subscriber units when communicating by way of the networks  14  and  16  and also when communicating by way of the GSM network  16 . 
     Mobile application part (MAP) interfaces are introduced into the mobility servers  48  and  52 , respectively. In one embodiment, five MAP operations are supported by the MAP interface. Namely, update location, insert subscriber data, delete subscriber data, cancel location, and provide roaming number operations are supported by the MAP interface. Such operations are performed, as necessary, to permit communications with the subscriber unit when the subscriber unit roams beyond its home network. 
     Subscription information associated with mobile subscriber units, such as the subscriber unit  58 , operable in the DECT network  14  are stored not only in the mobility server  48  but also in the HLR  36 . Services pursuant to the subscription in the HLR  36 , however, need not be defined. But, the subscriber unit  58  includes an MSISDN number and an IMSI number allocated thereto. The subscription for the subscriber unit in the HLR  36  is based on such numbers. 
     The mobility server  48  contains tables permitting transformation between a DECT identity, used to identify the subscriber unit in the DECT system  14  and the MSISDN and IMSI numbers, used to identify the subscriber unit in the GSM network  12 . 
     The DECT identity, the IMSI, and the MSISDN allocated to the subscriber unit  58  are further defined in each mobility server, such as the mobility server  52 , in each DECT system  16 , or other PTN, in which the subscriber unit  58  is permitted to roam. Such information is predefined in the mobility servers. Such predefined information further includes a predefined service profile which, in one embodiment, is not otherwise transferred from the subscriber units&#39;  58  home mobility server, here server  48 , to a visited mobility server, here server  52 . Each mobility server further includes a series of roaming numbers which are defined in manners similar to the roaming numbers defined in a mobile services switching center or location register of a conventional GSM network. Signaling between the MSCs  24  and  26  and the HLR  36  is routed by using a global title (GT) and subsystem number (SSN). Thereby, the mobility servers  48  and  52  appear to the HLR  36  as mobile services switching centers, similar to the switching centers  24  and  26 . The mobility servers further include unique MSC/VLR addresses, similar to the MSC/VLR addresses which identify the MSCs of the macrocellular network  12 . 
     FIG. 2 illustrates again the HLR  36  of the GSM network  12  and the mobility servers  48  and  52  of the DECT systems  14  and  16 , respectively. Lines  44  and  46  are  1 again shown to couple the HLR  36  with the mobility servers  48  and  52 , respectively. And, the radio exchange equipment  54  and  62  are again shown to be coupled to the respective mobility servers  48  and  52 . When a mobile subscriber unit, here subscriber unit  58 , roams out of the microcellular network  14 , its home network, and into the microcellular network  16 , the subscriber unit  58  registers with the mobility server  52 . The roaming of the subscriber unit is indicated in the figure by the arrow  84 . The identity of the subscriber unit  58  is indexed against a list of subscriber units permitted to roam. A subscriber unit  58  is assumed to be listed on such list and a transformation between the DECT identity of the subscriber unit  58  and its corresponding IMSI number is performed by the mobility manager  72 . 
     Second, as indicated by the arrow  86 , the mobility server  52  updates the location information of the subscriber unit with the HLR  36 . Then, and as indicated by the arrow  88 , the HLR  36  provides the mobility server  52  with subscriber data, namely the IMSI and MSISDN numbers, stored in the HLR  36 . And, as indicated by the arrow  92 , the HLR  36  causes the mobility server  48  to deregister the old registration of the subscriber unit  58  in the network  14 . Thereby, the location of the subscriber unit  58  is updated to indicate its location in the area encompassed by the microcellular network  16 , not the microcellular network  14 . 
     FIG. 3 illustrates operation of an embodiment of the present invention by which a call is routed to the subscriber unit  58 , regularly registered at the network  14 , when the subscriber unit  58  roams into the network  16 . Elements of the communication system  10  utilized in the exemplary operation of call routing to the roaming, subscriber unit  58  are shown in FIG.  3  and identified by the same reference numerals used to identify such elements in FIG.  1 . 
     When the mobility server  48  receives a call, such as a call originated at the PSTN to be terminated at the mobile subscriber unit, the identity of the subscriber unit is indexed against a list of subscriber units permitted to roam. The subscriber unit  58  is assumed to be on the list and marked as being roaming beyond the network  14 . The mobility manager of the mobility server  48  translates the DECT identity of the subscriber unit into an MSISDN number, and the call is routed to the MSC  24 , here forming a gateway MSC (GMSC). Such routing is indicated in the FIGURE by the arrow  102 . Then, and as indicated by the arrow  104 , the MSC  24  interrogates the HLR  36  for routing information to route the call to the roaming, subscriber unit. 
     Responsive to the interrogation, the HLR  36  requests a roaming number, MSRN, from the mobility server  52 , as indicated by the arrow  106 . The mobility server  52  returns the roaming number allocated to the subscriber unit  58  to the HLR  36 , as indicated by the arrow  108 . The HLR  36  thereafter, and as indicated by the arrow  112 , returns the roaming number allocated to the subscriber unit  58  to the MSC  24 . Once the roaming number is received at the MSC  24 , the call is routed to the roaming, subscriber unit  58 , as indicated by the arrows  114 , by utilizing the roaming number. The MSC  24 , in one embodiment, generates both a transit call data record and a roaming call forwarding record, for billing purposes, if desired. 
     FIG. 4 illustrates operation of an embodiment of the present invention by which the wide-area management functions provided by the GSM network  12  of the communication system  10  are utilized to facilitate routing of a call originated at a roaming subscriber unit, here subscriber unit  52  to a mobile subscriber unit operable in the GSM network. Again, elements of the communication system  10  utilized during such operation are identified with the same reference numerals utilized to identify such elements in FIG.  1 . 
     The subscriber unit  58  originates a call, indications of which are received by the radio exchange equipment  62 . The call request is provided to the mobility server  52  and the mobility manager  72  thereof indexes the identity of the roaming, subscriber unit against a listing of subscriber units permitted to roam. The subscriber unit is assumed to be on the list and the predefined service profile associated therewith is used for the subscriber unit  58 . 
     The call is set up by way of the MSC  26 , here forming a gateway MSC (GMSC) and the DECT identity of the subscriber unit  58  is used as an A-number. The call is thereafter routed, in conventional fashion pursuant to the GSM network, to be terminated at the mobile subscriber, here a mobile subscriber  122 . That is to say, the MSC  26  interrogates the HLR, as indicated by the arrow  124 , for routing information. Such routing information is received at the HLR  36  from the MSC  24 , as indicated by the arrow  126 , and a visited location register (not shown) associated therewith. The routing information is provided to the MSC  26 , as indicated by the arrow  128 . Responsive to the routing information, the call is routed from the MSC  26 , to the MSC  24 , as indicated by the arrow  130 , and thereafter to the appropriate base station  18 , as indicated by the arrow  132 . The call is thereafter terminated at the mobile station  122 , as indicated by the arrow  134 . 
     FIG. 5 illustrates operation of an embodiment of the present invention which permits routing of a call originated by a roaming, subscriber unit, here subscriber unit  58 , to another subscriber unit, here subscriber unit  136 , positioned in another DECT network, here DECT network  14 . The roaming, subscriber unit  58  generates a call to the subscriber unit  136 . The identity of the subscriber unit  58  is indexed against a list of permitted roaming subscriber units. The subscriber unit  58  is assumed to be listed on the list, and a predefined profile is allocated to the subscriber unit. The identity of the subscriber unit  136  is also indexed against a list of permitted roaming, subscriber units. Here, the subscriber unit  136  is assumed not to be listed upon the list of subscriber units permitted to roam. The call is thereby routed as an ordinary call between two DECT networks. 
     FIG. 6 illustrates a communication system, shown generally at  200 , of another embodiment of the present invention. The communication system  200  is, analogous to the communication system  10  shown in FIG. 1, a multi-network communication system, again including a microcellular communication network  12  and at least two microcellular communication networks, here communication networks  14  and  16 . The networks  12 ,  14  and  16  include the same elements as those previously shown in FIG.  1 . Such corresponding elements are again identified by the same reference numerals as those used in FIG.  1 . 
     Again, the macrocellular communication network  12  forms a GSM communication network having base stations  18 , each of which defines a cell  20 . The base stations  18  are coupled via the base station controllers  22  to mobile services switching centers (MSCs), such as the MSC  24  and  26 . The MSCs  24  and  26  are connected together by way of lines  28 . 
     The MSCs  24  and  26  are also coupled to a PSTN, here indicated by way of lines  32  and  34 , respectively. The MSCs  24  and  26  are further coupled to an HLR  36  by way of lines  38  and  42 , respectively. 
     The network  14  includes a mobility server  48 , and the network  16  includes a mobility server  52 . The mobility server  48  is coupled to radio exchange equipment  54  which includes radio transceivers for communicating with mobile subscriber units, such as the mobile subscriber unit  58 . And, radio exchange equipment  62  is coupled to the mobility server  52  by way of lines  64 . 
     The mobility server  48  is again shown to include a mobility manager  66  and a storage device  68 . And, the mobility server  52  is again shown to include a mobility manager  72  and a storage device  74 . The mobility server  48  is coupled to the MSC  24  by way of lines  76 , and the mobility server  52  is coupled to the MSC  26  by way of lines  78 . 
     In the communication system  200 , the HLR  36  is not directly coupled to the mobility servers  48  and  52 . Rather, the HLR  36  is indirectly coupled to the mobility servers by way of the Internet  242  which here forms an internet communication channel indirectly connecting the HLR  36  and the mobility servers  48  and  52 . The Internet  242  forms a connection between the HLR  36  and the mobility servers. 
     The mobility server  48  is coupled, such as by way of a local area network (hot shown in the figure) to a TCP mobile application part (TCP/MAP)  244 . The TCP/MAP  244  encapsulates information to be transmitted to the HLR  36  according to an internet protocol (IP), or other appropriate protocol. Similarly, a TCP/MAP  246  encapsulates data to be transmitted to the mobility server  48  according to an internet protocol, or the like. 
     The TCP/MAP  244  is further operable to de-encapsulate information transmitted thereto. And, similarly, the TCP/MAP  246  is further operable to de-encapsulate information transmitted thereto. In like fashion, TCP/MAPs  248  and  252  encapsulate and de-encapsulate data to be transmitted between the HLR  36  and the mobility server  52  to permit its transmission by way of the internet  242 . Because the internet permits communications to be effectuated between the HLR  36  and the mobility servers  48  and  52  without requiring that a direct connection be formed therebetween, security issues arising when an operator of the network  12  differs with the operator, or operators, of the networks  14  and  16  are avoided. Direct signaling, such as CCITT  7  signaling, is not required to effectuate communication of information needed to provide the networks  14  and  16  with the wide-area mobility functions of the network  12 . 
     Operation of the present invention permits wide-area mobility management functions provided by a macrocellular communication network to be utilized by a microcellular communication network to facilitate communication with a mobile subscriber. A mobile subscriber regularly registered in one microcellular communication network can roam to another microcellular communication network and utilize the wide-area mobility permitted in a macrocellular communication network to route calls to the roaming, subscriber unit. 
     The previous descriptions are preferred examples for implementing the invention, and the scope of the invention should not necessarily be limited by this description. The scope of the present invention is defined by the following claims.