MXPA01001392A - Method and apparatus for implementing international wireless roaming - Google Patents

Abstract

A method and apparatus for implementing international wireless roaming allows an international"roamer"to enter a visited system in a foreign country and originate calls. Upon entering the visited region, the roamer's mobile station initiates a registration request containing the mobile station's mobile identification number to the mobile switching center in the visited region. The mobile switching center initiates a message to an appropriate home location register. The home location register compares the mobile station's mobile identification number to a set of stored values. If an agreement is in place between the home location register provider and the roamer's home service provider, the home location register will return an appropriately formatted North American Numbering Plan mobile directory number to the mobile switching center. When the roamer initiates a call, the mobile switching center uses the mobile directory number in signaling call related information, specifically in populating parameters such as the Calling Party Number. Recognizing a NANP-formatted number, the public switch telephone network will process the call as normal.

Description

METHOD AND APPARATUS FOR IMPLEME TAR INTERNAL MBRICO INTERNATIONAL MONITORING BACKGROUND OF THE INVENTION 5 1. Field of the Invention The present invention is directed to international wireless communications and, more particularly, to a method and apparatus for facilitating service for international followers in a cellular system. 10 2. Background Cell phones ("cell phones") have become increasingly popular to provide immediate access to homes and workplaces from faraway locations. Not being already prohibitively expensive, telephones cell phones are used by a wide range of consumers. Currently, there are more than 75 million mobile phone consumers around the world. Predictions show that more than 300 million consumers will be using cellular systems by the year 2000. The telephones and cellular systems that are being introduced to the market, have advanced features and services as well as advantageous costs over previous cellular technologies. A cellular customer (a "subscriber") obtains cellular service within a region by subscribing to a wireless service provider ("WSP") (wireless service , ^. , ". _v *. M **? S¡? A ~ < ? t * -ana. . , iilllfffWWllT-ir i- • -SeA '--- - • ^ - ^ - provider) that is authorized to provide the service for that region. A single WSP uses many small areas of radio coverage ("cells") to serve hundreds of thousands of apples. The WSP depends on the Mobile Switching Center 5 ("MSC") to interconnect small radio coverage areas to a larger system as well as accept and send calls to other networks, ie the public switching network Telephone (PSTN) (public switcher telephone network). To keep a call When the cell phone is moved to another cell, the WSP switches the radio channel frequency of the telephone to another frequency available for use in an adjacent cell site. A frequency can be re-used by more than one client at the same time in different cells without subscriber interference if they are far enough away. WSPs take advantage of this by breaking up the coverage area into many small cells. Adjacent cells use different frequencies to avoid interference, but widely separated cells can reuse the same frequencies. This allows WSPs to repeatedly reuse radio channels and increase the number of subscribers that can serve with a limited number of channel frequencies. Each cell phone (or "mobile station") uses a unique signal identifier when operating in a system cell phone. This information is stored in its internal memory, called the Number Assignment Module ("NAM") (Number Assignment Module). The NAM also contains a Mobile Identification Number ("Mobile Identification Number"), a local system identifier, access classification and other information. The MIN value is usually the same value as the mobile directory number of the subscriber ("MDN") (mobile directory number), also known as the telephone number. The format of the telephone number for the United States, Canada and several US territories. is based on the North American Numbering Plan ("NANP"). This plan defines a format based on a three-digit Numbering Plan Area ("NPA") (Numbering Plan Area), a three-digit central office code ("NXX") and a subscriber line number of four. digits ("XXXXs"). (This is often denoted using an NPA-NXX-XXXX format where N = digits from 2 to 9 and X = digits from 0 to 9). Since the MIN value is the same as that of the MDN, it is also implemented as a ten-digit number that follows the NPA-NXX-XXXX format. Frequently, WSPs allow customers of other cellular systems to use their service. The ability of a subscriber to use the service of a different WSP is called "tracking". A common type of tracking is "automatic" tracking and is initiated by a - * "• - '" •' - lgg m ^ - process called registration. The registration of a follower occurs as follows: When a mobile station detects a foreign cellular system, it tries to register it with the system. This is done by signaling, among other things, its MIN value and its electronic serial number. The service system searches for the MIN of the cordless telephone in its visitor location register ("VLR") (visitor location register) and determines that the cordless telephone is not yet registered. The visited cellular system uses the MIN and the ESN of the wireless telephone to request the validation of the subscriber's identity from the subscriber's local cellular system, specifically the Local location register (("HLR") (Home location register). will then determine if the subscriber is valid and recognizes the status for the requesting cellular system The visited VLR temporarily stores the subscriber's registration information for future authorizations, eliminating the need to make contact with the subscriber's local HLR if a new one is processed Once validated, the mobile station can receive and originate calls in a transparent manner After a predetermined period of inactivity, the temporary authorization information stored in the VLR is erased.The communication between the VLR and the HLR frequently uses a network is signaling known as Signaling System 7 ("SS7"). Each of the entities in the network, for example the VßR and the HLR, are identified by a unique address called a point code. In many cases, a separate network entity, called a signal transfer point ("STP"), is used to derive the HLR point code based on the tables associated with the MIN value. The VLR can send the registration request to the STP which then derives the appropriate HLR point code based on the MIN. The STP derives the appropriate HLR address based on the first six digits (corresponding to the NPA-NXX portion of the directory number). During the period in which the mobile station registers in the VLR, the mobile station can originate calls. During the origin of the call, the MSC uses the stored MIN as the telephone number associated with the follower. This value is used in SS7 signaling parameters of certain populations such as the "Calling Party Number" parameter. Although automatic home tracking is quite common, international automatic tracking presents great difficulties. Subscribers of cell phones from outside the United States, Canada and US territories often do not enjoy the benefits of automatic tracking when entering the country. Frequently, mobile subscribers can not register successfully, which results in the service being denied; or if they have a successful registration, long-distance calls can not be successfully completed. Calls made to foreign countries (which are of particular interest to international supporters) are normally completely restricted. According to the above, the utility of the cellular service for an international follower is drastically reduced. The problems associated with a mobile station registration are due to three problems: (1) The necessary registration procedure to establish a call often requires the existence of certain international business relationships; and (2) Several countries around the world have adopted different (and often incompatible) numbering plans; and (3) The frequent prohibition of international calls imposed on subscribers by many US cellular service providers. The registration procedure requires that the visited WSP have a direct or indirect commercial agreement to provide the service to the local service providers. Although in the US, most cellular telecommunications companies have established tracking agreements directly with other telecommunications companies or use the service center ^ n ^ -J? J- ** - - reference to facilitate this, this is often not the case among international cellular service providers. Assuming that such follow-up trade agreements are in place, there are technical issues with respect to the transfer of signaling information between the VLR and the HLR. As previously described, this signaling information is transported over the SS7 network and requires that each entity be assigned an address known as a point code. However, the service provider external to the US can not obtain the address of the point code within the numbering space allocated in the US. Preferably, the signaling must be directed to an international access means that can direct such message. Unfortunately, few international means of access, if any, have been established. This significantly limits the ability of a mobile station to register automatically. Assuming that the registration could occur successfully, the mobile station would be authorized to initiate a call. However, problems can occur with the establishment of the call that prevents the automatic tracking service. One of these problems is to investigate the differences between telephone numbering plans of the US and other countries that are not part of the NANP. When the mobile station originates a call, the MSC ^ ¡Í uses the value of the stored MIN as the number of the calling party to signal the establishment of the call to the PSTN. Coronatization of the local PSTN (or the subsequent switching of the telecommunications exchange company) can examine the calling party's number to verify the subscriber that originates it. The determination includes whether the portion of the NPA corresponds to a currently assigned area code, as well as whether the NXX portion is properly formatted. If any of these portions corresponds to a combination of invalid NPA-NXX-XXXX, the PSTN switch may consider the telephone number invalid. This could happen if the number is derived from the MIN of the mobile station since it would be based on the numbering plan of the country of origin of the subscriber. Many telecommunications companies in the US they would finish the processing of the call. The final aspect that limits the international tracking service is that which results from the limitations imposed by many US cellular service providers, many of which currently prohibit any international call by any subscriber either by tracking or not, partially by referring to losses due to fraud. This would provide that international supporters would often like to call j¿¿s ÜÜ-HÍÍi ^ by phone to your country of origin; By prohibiting such calls, the international tracking service is obviously limited. SUMMARY OF THE INVENTION A preferred embodiment of the present invention overcomes the problems and disadvantages of the prior art by providing a local HLR that receives the registration request that contains the MIN of the international follower. The HLR correlates this MIN to a mobile directory number that then returns to the local service switch during registration. The mobile directory number is a number formatted with the Numbering Plan of North America that is indirectly associated with the MIN of the international follower. When the international follower initiates a call, the service switch uses the mobile directory number returned by the HLR as the calling party number. Since the number is formatted with the NANP, any PSTN switch will consider the calling party number to be appropriately valid and, therefore, will continue the process of the call. To overcome the problem of terminating international calls, the tracker can complete a local call that ends in a system that can then allow the user to terminate an international long distance call. This is done partly by correlating the MIN of international base to m¡ HLR local within the cellular telephone network. This is established in industrial agreements that assume that the first four digits of certain MIN values correspond to an identification code of the international network. A signal transfer point uses the identification code within the MIN to direct messages from the service switch to the appropriate local location register. The HLR associates the MIN of the international mobile station with a mobile directory number that returns to the service switch. In accordance with the purpose of the invention, as embodied and broadly described herein, the invention is a method for facilitating cellular service in a service system visited from a cell phone that stores a mobile identification number, the method comprises the steps of sending a registration notification from a service switch to an HLR; sending an acknowledgment from the HLR to the service switch, including recognition a mobile directory number associated with the mobile identification number; and, when the cell phone originates a telephone call, the service switch uses the mobile directory number as a calling party number for signaling purposes. fe ^ ato, .. ^ M .. ^ .... 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- - The objects and advantages of the invention will be set forth in part in the following description and in part will be obvious from the description or can be learned by practicing the invention. The objects and advantages of the invention will be realized and achieved by means of the elements and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of an international tracking network architecture according to a preferred embodiment of the present invention. Figure 2 is a block diagram of the cellular telephone unit, according to a preferred embodiment of the present invention. Figure 3 is a flow diagram illustrating the steps performed within the architecture of the network of Figure 1 during the activation and registration of the mobile station within a visited service region. Figure 4 is a flow chart illustrating the steps performed during an international long distance call from a mobile station. Figure 5 is an illustration of a Call Establishment Request, in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES ^^ £ &j Will reference now be made to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. Figure 1 is a block diagram of an international tracking network architecture, according to a preferred embodiment of the present invention. The architecture includes a mobile station 100, such as a cellular telephone or PCS, operated by an international cellular telephone follower. The follower is pre-registered with a Local Service Provider ("HSP") (Home Service Provider) located in a service region 165 located outside of North America. The HSP controls a Foreign Mobile Service Switching Center 180 ("FMSC") (Foreign Mobile Service Switching Center) that interconnects the mobile equipment with the wired telephone network of the foreign country. A Foreign Local Location Record 185 ("FHLR") (Foreign Home Location Register) is a subscriber database containing each Mobile Identification Number ("MIN") and Electronic Serial Number ("ESN") (Electronic Serial) Number) of the client to uniquely identify each client, including the operator of the mobile station 100. The FMSC 180 uses this information stored in the FHLR 185 to authorize access to the system and the process of ^ g | ¡^ n ^^^^^ .j ^ ^^ - ñ? ^, individual invoicing of the call. The FHLR 185 can be a magnetic storage device for a computer. Figure 2 is a block diagram of the cellular telephone unit 100, according to a preferred embodiment of the present invention. The cellular telephone 20 includes the processor 222 capable of processing the messages received by the cellular telephone unit 100 using the known hardware and according to known methods. To make each mobile phone unique, several types of information are stored in the internal memory. This memory is called Number Assignment Module 230 (Number Assignment Module (NAM)). The NAM contains a Mobile Identification Number 228, which identifies the mobile station 100. The mobile station 100 further includes additional circuitry 223 for transmitting and receiving data. In Figure 1, the "international follower" initiates a call from within the visited system 130. A Wireless Service Provider ("WSP") provides cellular service within the system 130. The WSP controls a Mobile Switching Center ("MSC"). or "switch") 110 that interconnects the mobile equipment with a wired telephone network in North America. In particular, the MSC 110 is connected to an SS7 cellular telephone network, which may include one or more 140 signal transfer points, and Location Registration < AM ~ - * ~ - - - "^" "" lluff "- ^ - ~ .-- ~ - ^ -. - .. ^ ¿..ito.-mtft ....-Local International Tracking Service 160 ("IRS HLR") International Roaming Service Home Location Register.) MSC 110 creates SS7 messages and routes these messages through STP 140. STP 140 is responsible for directing traffic and is not the originator of any traffic or final receiver of no traffic The SS7 signaling is described in detail in the "Telecommunications Protocols" by Travis Russell, published in 1997 by McGraw-Hill Companies, Inc., which is incorporated herein by reference.The IRS HLR 160 It works as a local location record, but includes additional logic to perform international tracking, as described here.According to a follow-up agreement between the WSP and the follower's HSP, the WSP occupies the IRS HLR 160 with the MIN and the ESN of the subscribers of the specific HSP, including the international follower. The mobile station 100 is routed to the correct IRS HLR 160 using a correlation with the first four digits of the MIN 228 to a point code of the SS7 for the IRS HLR 160. According to the International Forum on AMPS Standards Technology (" IFAST "), the first four digits of MIN 228 correspond to an International Network Identification Code (" INIC ") (International Network Identification Code). The INIC is pre-dependent on the national cellular number. The INIC is in the format of "0/1 XXX" K ^ ÉMtat. where the first digit is either "0" or a "1" and the next three digits can be "0" to "9". Each INIC is correlated with a point code SS7 (address) for an IRS HLR. Thus, in the example illustrated in Figure 1, the 5 INIC for the mobile station 100 could be correlated to a point code for the IRS HLR 160. Figure 3 is a flow diagram illustrating the steps performed within the architecture of the network of Figure 1 during the activation and registration of the station mobile within a visited service region 130. In a first step 302, upon activation in a region served by the WSP, the mobile station 100 initiates a registration request for the MSC 110. The request includes the MIN (including INIC) and the ESN of mobile station 100. In In step 304, the MSC 110 associates the INIC with a point code SS7 by means of the correlation described above. In step 306, the MSC 110 initiates an IS-41 message, called the Registration Notification to the IRS HLR 160 using the elements of the SS7 network. The IS-41 signaling is described in the Electronics Industry Association / Telecommunications Industry Association "Provisional Standard -41, Revision C" which is incorporated herein by reference. The Notification of Registration message similarly contains the MIN and the ESN of the follower. In step 308, the IRS HLR 160 compares the MIN and the Jg-ik "t -" - "- ~" "- ~ ^ 'i -a-aSa, ^ - * - * ¡& u * ^. ..... Iifefc-. _-.

- ESN to the values stored in the IRS HLR 160. If the values are found, the IRS HLR 160 confirms that the mobile station 100 is a valid subscriber. If the values are not found, the IRS HLR 160 will report an error in step 312. An error normally occurs when an agreement has not been established between the visited service provider and the local service provider of the follower. In step 314 the IRS HLR 160 returns an acknowledgment to the MSC 110. The recognition includes a Mobile Directory Number ("MDN") formatted with the NANP for the MIN. The IRS HLR 160 selects the MDN from a group of numbers assigned to serve international supporters. The MDN is now associated with the original MIN. The MSC 110 will use the MDN to occupy the parameter of the calling party number for any call coming from the mobile station 110 within the visited system 120. Figure 4 is a flow diagram illustrating the steps performed during a call coming from the mobile station 100. In step 402, the mobile station 100 originates a long distance call by sending the long distance call request to the MSC 110. The request includes the desired destination telephone number. The MSC 110, in step 404 uses the services of the telecommunications exchange company 195 ("IXC") (Figure 1) for end this call. The IXC is a long carrier Wired line distance that includes switching equipment to switch calls to international switching centers. In particular, the MSC 110 transmits a Call Establishment Request to the IXC 195. The Call Establishment Request is formatted according to the SS7 ISUP IAM standard. Figure 5 is an illustration of a Call Establishment Request 410. The request 410 includes a Calling Party Number field 415 and a Calling Party Number field 420. The MSC 110 occupies the Number field of the Calling Party. calling party 420 with the destination number based on the dialed number. Preferably, using the MIN of the mobile station 100 (which may or may not be a number formatted with the NANP), the MSC 110 occupies the field of the calling party number 415 with the MDN previously returned during registration by the IRS HLR 160. The complete call establishment request 410 is then transmitted to the IXC 195. The IXC 195, in step 406, examines the field of the calling party number 415 of the request 410. By recognizing a number formatted with the NANP , the IXC, in step 412, connects the call to the called party. If the number formatted with the NANP was not provided in step 404, the IXC would report an error back to the MSC. The call would not be completed. To complete international calls, this - it is carried out by means of the mobile station that establishes a local call that ends in a system that uses the previously described methods, then allowing the calling party to terminate an international long distance call. Having thus described a preferred embodiment of a method and apparatus for international wireless tracking, it will be apparent to those skilled in the art that certain advantages have been achieved. It will also be apparent that various modifications, adaptations and alternative embodiments thereof may be elaborated within the spirit and scope of the present invention. The invention is further defined by the following claims. The invention is further defined by the following claims.

Claims (20)

1. CLAIMS 1. A method for facilitating the mobile telephone service within a cellular system visited at a foreign mobile station having a foreign mobile identification number, the method comprising: transmitting the foreign mobile identification number from the foreign mobile station to the cellular system visited; accessing a local location registrar of the international tracking service within the visited cellular system, where the local location registrar of the international tracking service is engaged with a plurality of subscribed foreign mobile identification numbers, to determine that the mobile station is a subscriber; associate a formatted mobile directory number with the North American Numbering Plan with the foreign mobile identification number; transmitting the mobile directory number of the NANP to the switch serving the mobile station; and using the mobile directory number NANP within the switch when the foreign mobile station originates a call.
2. 2. The method for facilitating the cellular telephone service as cited in claim 1, in ^ ¡¡G 3Ü * '- «> * - where transmitting the foreign mobile identification number also includes: directing the foreign mobile identification number to the local location register of the international tracking service.
3. 3. The method for providing the cellular telephone service as recited in claim 2, wherein the foreign mobile identification number is directed to the international tracking service of the local location register based on the first four digits of the identification number foreign mobile.
4. 4. The method for providing the cellular telephone service as recited in claim 2, wherein the foreign mobile identification number is directed to the local location register of the international tracking service based on a plurality of digits in the number of foreign mobile identification.
5. The method for providing the cellular telephone service as recited in claim 4, wherein the step of directing the foreign mobile identification number to the local location record of the international tracking service includes associating the plurality of digits with a code point of the Signaling System # 7 of the local location record of the international tracking service. ,TO
6. 6. The method for facilitating the cellular telephone service as cited in claim 2, wherein transmitting the foreign mobile identification number to the local location registration of the service of 5 international monitoring further comprises: transmitting a registration request containing the foreign mobile identification number to the switch serving the mobile station; and transmit the registration notification of IS-41 10 from the switch to the local location record of the international tracking service.
7. 7. The method for providing the cellular telephone service as recited in claim 2, further comprising determining that the foreign mobile station 15 is a subscriber when comparing the foreign mobile identification number to the plurality of foreign mobile identification numbers subscribed to find an equalization.
8. 8. The method for facilitating the cellular telephone service as cited in claim 2, in Wherein transmitting the mobile directory number of the NANP to the switch further comprises transmitting a call setup request containing the mobile directory number of the NANP for the switch.
9. 9. The method for facilitating the cellular telephone service as cited in claim 8, in ._ ^. ^ _. ' jb ^ -_. " . "... ...".? ... .. «-., ... JM. .33M »-. .. - where the mobile directory number of the NANP occupies a field of the calling party of the call establishment request.
10. 10. The method for providing cellular telephone service within a cellular system visited from a foreign mobile station that has a foreign mobile identification number, the method comprises: transmitting a registration notification from a switch serving the foreign mobile station to a local location record of international tracking service in the visited service system, where the local tracking record of tracking service International deals with a plurality of foreign mobile identification numbers subscribed; transmit an acknowledgment from the local location record of international tracking service to the switch, including recognition a mobile directory number formatted with the North American Numbering Plan (NANP) associated with the foreign mobile identification number; and transmitting the mobile directory number of the NANP as a calling party number for the foreign mobile station where the foreign mobile station originates a telephone ca
11. ll. The method for providing the cellular telephone service as recited in claim 10, comprising: associating the foreign mobile identification number with an address of the local location register 5 of the international tracking service; and direct the registration notification to the local location record of the international tracking service based on the foreign mobile identification number.
12. 12. The method for providing the cellular telephone service as recited in claim 10, further comprising: associating the first four digits of the mobile identification number with an address of the local location record of the international tracking service within a net; and direct the registration notification to the local location record of the international tracking service based on the foreign mobile identification number 20.
13. The method for providing the cellular telephone service as recited in claim 10, wherein the mobile directory number is transmitted as a number of the calling party to another switch. 25 14.
14. The method to facilitate the service cellular telephone as recited in claim 13, wherein the other switch is a telecommunications exchange company switch.
15. The method for providing the cellular telephone service as recited in claim 14, wherein transmitting the mobile directory number of the NANP to the other switch further comprises transmitting a call setup request containing the mobile directory number of the NANP towards the telecommunications exchange company.
16. 16. A visited cellular system that provides service to a foreign mobile station that has a foreign mobile identification number and operates in an area of the visited cellular system, the system comprising: a switch in the visited cellular system operating to receive the number foreign mobile identification (MIN) from the foreign mobile station, and to transmit the foreign MIN to a local location registry of international tracking service (IRS HLR); the IRS HLR being located in the visited cellular system to store a plurality of subscribed foreign mobile identification numbers (MINs) and, if the foreign MIN received by the switch in the visited cellular system is among the subscribed foreign MINs, to transmit a number of mobile directory formatted with the North American Numbering Plan (NANP) associated with the foreign MIN for the commutation in the visited cellular system; and the switch is also operative in the system 5 cell visited to receive the mobile directory number of the NANP from the IRS HLR and to use the mobile directory number of the NANP when the foreign mobile station originates a call in the visited cellular system.
17. 17. The cellular system visited as recited in claim 16, further comprising a telecommunications exchange company switch that operates to receive information related to the foreign mobile station from the switch in the visited cellular system, including the information the mobile directory number 15 of the NANP.
18. 18. The visited cellular system, as recited in claim 16, wherein the local location record of the international tracking service (IRS HLR) stores a plurality of mobile directory numbers of the NANP. 20 assigned reserved to be assigned to subscribed foreign mobile stations.
19. 19. The visited system, as recited in claim 16, wherein the switch in the visited cellular system transmits the foreign MIN in association 25 with the registration notification IS-41 towards the registration of ^^^^^^; ^^ ^ ja ^ lijj ^ tí ^^^^^ local location of the international tracking service (IRS HLR).
20. 20. The visited system, as recited in claim 16, wherein the switch in the visited cellular system uses the mobile directory number of the NANP by occupying a field of the calling party of a call set-up request with the number of the NANP mobile directory. ^ - ^^ É - ^^^^