Abstract:
A system and method for providing portability of internet addressing maintains additional IP addressing information in number portability databases located throughout provider domains in a telecommunications network. This additional IP addressing information, in conjunction with additional Number Portability Request messaging information, permits portability of addresses across telecommunication and data communication networks in a transparent fashion.

Description:
BACKGROUND 
     Applicants&#39; invention relates generally to number portability in telecommunications systems and, more particularly, to techniques for providing number portability towards Internet service providers. 
     Number portability in telecommunication systems typically permits end users (i.e., mobile subscribers) to retain the same telephone numbers whenever the end users change from one telecommunication service provider/operator domain to another telecommunication service provider/operator domain. Without number portability, service providers will be unable to accommodate the relocation of a mobile subscriber from one service provider to another without changing the subscriber&#39;s directory telephone number. 
     Changing a directory telephone number in the event of relocation of a subscriber occasions expense and effort for both the subscriber and the telecommunications provider. For the provider, it is an expensive process to administer the changes of directory telephone numbers when a subscriber relocates from one area to another. The administration required by the provider includes both efforts to define available new numbers in the new location and to update the existing directory. The relocated subscriber also incurs expense in providing notice of the new directory number to potential callers (friends and business contacts). If such notice is not provided or retained by the potential callers, calls may not be placed to the relocated subscriber. Loss of calls to a relocated subscriber can result in loss of social or business opportunity. Thus, number portability is advantageous in that it permits relocated mobile subscribers, who have changed service providers, to receive calls that otherwise might be directed to the wrong service provider and therefore would be lost. 
     For an understanding of number portability, a conventional telecommunications network  10  is shown in FIG.  1  and is described below. Network  10  includes a set of service provider domains  20 A- 20 C and  20 F. Three of the domains (particularly domains  20 A- 20 C) are mobile telecommunications domains serving mobile stations; domain  20 F serves fixed stations. In the illustrated network, domain  20 F can be of a network type such as a public switched network (PSTN) or integrated services digital network (ISDN), for example. At least some of the areas served by domains  20  can be, and likely are, geographically coextensive. Some of the domains  20  may also be served by differing service providers, e.g., different telecommunications operating companies. 
     Fixed station domain  20 F includes at least one local exchange  22 F. Local exchange  22 F is connected to a plurality of fixed subscriber stations, only one of which (subscriber  24 ) is shown in FIG.  1 . Local exchange  22 F is connected either directly or ultimately (e.g., via transit exchanges) to a gateway exchange or gateway node  26 F. Gateway node  26 F is connected to a database  30 F. Database  30 F is, in turn, connected (e.g., for updating and maintenance purpose) to a service management system  32 F. 
     Mobile telecommunications domains  20 A- 20 C each have respective gateway nodes  26 A- 26 C, each of which takes the form of gateway mobile services switching center (GMSC) and accordingly are respectively referred to as GMSCs  26 A- 26 C. 
     Each gateway node GMSC  26  serves as an interface to external domains  20  for one or more mobile services switching centers (MSCs)  40  which belong to the domain. 
     Although any given domain likely has a plurality of MSCs  20 , only a single MSC  40  is shown in domains  20  for purposes of illustration. Each GMSC  26  is connected to the MSCs  40  in its domain; MSCs  40  in the same domain may also be connected. Each MSC  40  in FIG. 1 is connected to serve at least one and preferably a plurality of base station controllers (BSCs)  50 . For example, MSC  40 A serves base station controllers  50 A- 1  through  50 A-m; MSC  40 B( 1 ) serves base station controllers  50 B( 1 )- 1  through  50 B( 1 )-m. It should be understood that, typically, differing MSCs  40  serve a differing number of base station controllers  50 . The use of BSCs  50 , shown in the Figures, is for purposes of illustration. It will be recognized that each MSC  40  can directly serve the BSs  60  without any intermediary BSCs  50  in some mobile systems (e.g., TDMA according to IS-136). 
     Each base station controller  50  is connected to one or more base transceiver stations (BS)  60 A- 1  through  60 A-l(q). The number of base transceiver stations (BS)  60  per base station controller  50  can vary. 
     Each base transceiver stations (BS)  60  transmits and receives radio frequency communications to and from a plurality of mobile subscribers (MS)  70  in the geographical areas served by the respective BS  60 . For sake of simplicity and illustration, only one mobile station  70  is shown in FIG. 1, although it should be understood that each domain  20  serves hundreds if not thousands of unillustrated mobile stations. The particular mobile station  70  depicted in FIG. 1 is shown as being served by base transceiver station (BS)  60 A-m(q). 
     Mobile telecommunications domains  20 A- 20 C each include respective databases  30 A- 30 C. Databases  30 A- 30 C are connected to and maintained by service management systems  32 A- 32 C, respectively. Service management systems  32 A- 32 C are connected to and supervised by a master management system  32 M. 
     Databases  30  are subscriber location servers which are augmented with additional intelligence and are known as mobile subscriber number portability databases. Databases  30  include information which facilitates number portability for many types of subscribers in their respective domains, including mobile subscribers. 
     As will become more apparent below, the mobile telecommunications domains  20 A- 20 C described above comprise a mobile subscriber number portability domain. In the number portability domain, mobile subscribers can change service providers, e.g., change from one of the domains to another, e.g., change from domain  20 A to domain  20 C, and still maintain their “directory” number. FIG. 2 shows the circumstance where mobile subscriber  71  has changed service providers. In particular, as depicted in FIG. 2, mobile subscriber  71  has changed his subscription from the provider which operates domain  20 C to the provider which operates domain  20 B. In fact, at the time shown in FIG. 2, mobile subscriber  71  is served by MSC  40 B( 1 ). 
     Upon the change of subscription as depicted in FIG. 2, deletion of the subscriber (owning mobile station  71 ) from MSC  40 C was communicated to service management system (SMS)  32 C, which advised master service management system (SMS)  32 M. SMS  32 M subsequently communicated the deletion of the subscriber to all SMSs  32 , including SMSs  32 A,  32 B, and  32 F, which in turn updated respective databases  30 A,  30 B,  32 F, accordingly. Then, when the subscriber joined the service provider which operates domain  20 B, SMS  32 C advised master SMS  32 M of the enlistment. SMS  32 M subsequently advised all SMSs  32  of the enlistment in domain  20 B of the subscriber, including SMSs  32 A,  32 C,  32 F, which in turn updated respective databases  30 A,  30 C, and  30 F, accordingly. Therefore, in accordance with the above process, the subscriber of mobile station  71  is able to retain the same directory number upon changing service providers from domain  20 C to domain  20 B. 
     FIG. 2 further shows placement of a call from mobile subscriber  70  in domain  20 A to mobile subscriber  71  which has changed from service provider  20 C to service provider  20 B. The originating MSC  40 A receives the mobile subscriber call via BS  60 A-m(q) and BSC  50 A-m. Then, in accordance with conventional techniques, MSC  40 A initiates a number portability request message (Action  3 - 1 ; FIG.  2 ), such as, for example, the Number Portability Request Invoke message utilized in ANSI41, to number portability database  30 A. However, in view of the previous updating of database  30 A to reflect the mobile subscriber  71  changing service providers (as discussed above), the parameter returned by database  30 A at action  3 - 2  includes the address of the new GMSC  26 B, not the address of the old GMSC  26 C. Thus, at  3 - 2 , number portability database  30 A initiates a number portability return message, such as, for example, the Number Portability Request Return Result (npreq) utilized in ANSI41, to the originating MSC  40 A. This return message includes a local portability routing number (LRN) to GMSC  26 B. Thus, MSC  40 A can then connect the originating call from mobile subscriber  70  to GMSC  26 B, and thereby to MSC 40 B( 1 ), BSC  50 B( 1 )- 1 , BS  60 B( 1 )- 1 (a), and finally to called mobile subscriber  71 . Therefore, mobile subscriber  70  is able to call mobile subscriber  71 , which has changed service providers from  20 C to  20 B, using the same directory number. 
     Thus, as described above, a call-originating domain accesses a mobile subscriber number portability database to obtain the address of the gateway node of the telecommunications domain which currently serves a called mobile subscriber. Use of the Number Portability database will therefore advantageously permit a mobile subscriber in a telecommunications system to retain the same directory number whenever the subscriber changes from one service provider/operator domain to another service provider/operator domain. 
     Conventionally, however, the above described number portability database is usable only for telecommunication service providers and does not provide portability towards Internet service providers. Applying conventional number portability techniques to the portability of Internet addressing would be advantageous since both current and proposed (IPv6) Internet addressing systems are provider-based and therefore, whenever a subscriber changes providers, the subscriber&#39;s domain name changes as well as the subscriber&#39;s IP address. Therefore it would be desirable to extend application of the number portability database to permit a subscriber to change from one Internet access provider to another access provider without changing the subscriber&#39;s Internet IP address and/or domain name. Additionally, number portability can be applied to the internet service provider itself. Thus, if an internet service provider&#39;s IP address changes, then number portability can permit continued access by subscribers and/or other data communication network. Extending application of the conventional number portability database to Internet service providers therefore advantageously permits a cohesive integration between telecommunication and data communication networks. This integration would permit telecommunication network operators and data communications providers (e.g., internet service providers) to improve service to their subscribers by providing access between the two in a transparent fashion (i.e., telecom to datacom or datacom to telecom). Extending application of the conventional number portability database to internet service providers additionally permits number portability between data communications providers (i.e., datacom to datacom). 
     SUMMARY 
     These desirable characteristics and others are provided by the following exemplary embodiments of the invention. 
     According to one exemplary embodiment of the invention a method of routing calls through a communications network is provided. The method of this exemplary embodiment comprises the steps of: a) initiating a call from a first subscriber in a call-originating domain to a second subscriber in a data communications domain; b) transmitting a first message from a first node in said call-originating domain to a database in said call-originating domain; c) locating a current data communication network node parameter in said database, wherein said network node parameter is associated with said second subscriber; d) transmitting a second message that includes said located data communication network node parameter from said database to said first node; e) routing said call from said first node to a data communications address indicated by said located data communication network node parameter; and f) updating said database when said second subscriber changes membership from a first communication network provider to a data communication network provider. 
     According to a second exemplary embodiment of the invention a system for routing calls through a communications network is provided. The system of this exemplary embodiment comprises: means for initiating a call from a first subscriber in a call-originating domain to a second subscriber in a data communications domain; means for transmitting a first message from a first node in said call-originating domain to a database in said call-originating domain; means for locating a current data communication network node parameter in said database, wherein said network node parameter is associated with said second subscriber; means for transmitting a second message that includes said located data communication network node parameter from said database to said first node; means for routing said call from said first node to a data communications address indicated by said located data communication network node parameter; and means for updating said database when said second subscriber changes membership from a first communication network provider to a data communication network provider. 
     According to a third exemplary embodiment of the invention a method of routing calls through a communications network, the communications network having a set of domains, at least one of the domains in said set of domains being a data communications domain, is provided. The method of this exemplary embodiment comprises the steps of: accessing, in a call-originating domain included in the set of domains, a database to obtain an address of a node of the data communications domain which currently serves a called subscriber; and including the address of the data communications domain which currently serves said called subscriber as a parameter in a routing message for routing a call from the call-originating domain to said node of said data communications domain. 
     According to a fourth exemplary embodiment of the invention a system for routing calls through a communications network, the communications network having a set of domains, at least one of the domains in said set of domains being a data communications domain, is provided. The system of this exemplary embodiment comprises: means for accessing, in a call-originating domain included in the set of domains, a database to obtain an address of a node of the data communications domain which currently serves a called subscriber; and means for including the address of the data communications domain which currently serves said called subscriber as a parameter in a routing message for routing a call from the call-originating domain to said node of said data communications domain. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and advantages of the invention will be understood by reading the following detailed description in conjunction with the drawings in which: 
     FIG. 1 is a diagram of a conventional telecommunications network that implements number portability; 
     FIG. 2 is a diagram of a call from a first mobile subscriber to a second mobile subscriber that has changed service providers in a telecommunications network; 
     FIG. 3 is a diagram of message parameters of exemplary embodiments of the invention that are included in the Number Portability Request Invoke message; 
     FIG. 4 is a diagram of message parameters of exemplary embodiments of the invention that are included in the Number Portability Request Return Result message; 
     FIG. 5 is a flow diagram of exemplary embodiments of the invention; and 
     FIG. 6 is a diagram illustrating the messaging between system components in accordance with exemplary embodiments of the invention. 
    
    
     DETAILED DESCRIPTION 
     To provide portability of addresses across telecommunication and data communication networks, exemplary embodiments of the invention extend the conventional number portability principles, described in the Background section above, to include Internet addresses as well as the E.164 type of addresses currently returned as the local number portability routing digits. To account for Internet addressing, exemplary embodiments of the invention modify the conventional number portability request invoke messages (e.g., ANSI41 NPREQ) and the number portability request return result messages (e.g., ANSI41 npreq) to include additional information. For request invoke messages, this additional information will include a new parameter, “Transaction Capability,” that indicates whether Internet addressing is supported. For return result messages, the additional information will include a new optional routing address parameter, “Routing IP Address,” that will permit routing of the call on the IP network towards the ported Internet service provider (e.g., voice over IP), and a new “Ported Gateway Capabilities” parameter that specifies the protocol capabilities of the ported gateway. 
     FIG. 3 illustrates modification of the conventional Number Portability Request Invoke message  100  in accordance with exemplary embodiments of the invention. As discussed above, “Transaction Capability” flag  101  is added to the message  100  to indicate whether the originating mobile switching center/end user terminal/network node is capable of initiating Internet calls to a destination IP address. If the flag  101  is “set,” then the capability of supporting Internet addressing is indicated. Conversely, if the flag is “cleared,” then Internet addressing is not supported. 
     FIG. 4 illustrates modification of the conventional Number Portability Request Return Result message in accordance with further exemplary embodiments of the invention. In these further exemplary embodiments, a “Routing IP Address” parameter  103  is added to the Return Result message  102 . This “Routing IP Address” parameter is composed of sub-elements including Parameter ID  104 , Parameter Length  105 , Address Type  106 , and IP Address  107 . The Parameter ID  104  is an identifier or tag that specifies the type of information included in the message, the Parameter Length  105  specifies the length of the “Routing IP Address” parameter, the Address Type  106  specifies the type of IP address (e.g., IPv4, IPv6, ATM, etc.) contained in the “Routing IP Address” parameter, and the IP Address  107  specifies the IP address to which the called subscriber is ported. 
     In addition to the “Routing IP Address,” the protocol capabilities of the ported gateway will be included in a new “Ported Gateway Capabilities” parameter  130 . This parameter will specify the protocol capabilities of the ported gateway including options such as SIP, H.323, L2TP tunneling (IETF), PPP (point to point protocol, IETF), or ATM UNI. 
     It is noted that, though FIGS. 3 and 4 illustrate the additional parameters of exemplary embodiments as being appended to the end of the conventional Request Invoke and Return Result messages, one skilled in the art will recognize that these additional parameters could be located at any appropriate location within the messages. 
     In further exemplary embodiments of the invention, the conventional Number Portability database ( 30  in FIG. 2) can also be modified to support a new entry for IP addresses. Additionally, a “Name Address” entry could also be added to the NPDB. This “Name Address” entry could be used for performing conversion to an IP address before the NPDB answers a number portability request message. This conversion could be performed, for example, by querying a directory name server. For example, if the ported address is a text address (e-mail, URL, etc.), the NPDB would query a directory name server to request the IP address corresponding to the text address. This IP address can then be returned via the Return Result message ( 102  and  103  of FIG.  4 ). 
     A flow diagram of the operation of the exemplary embodiments discussed above is shown in FIG.  5 . When a communication is initiated  110 , the switching center/end user terminal/network node ( 117 , FIG. 6) will initiate  111  a Number Portability Request message ( 118 , FIG. 6) to the NPDB ( 30 , FIG. 6) which will include the “Transaction Capability” parameter. The NPDB then determines  112  whether the “Transaction Capability” parameter indicates that the MSC/end user terminal/network node is capable of initiating Internet calls to a destination IP address. If internet addressing is not supported, meaning that the originating domain is not able to set-up an internet call to the ported internet service provider, the NPDB will return  113  an LRN in E.164 format that is the address of the closest gateway to the ported internet service provider (ISP) capable of performing protocol conversion. If, however, Internet addressing is supported, the NPDB further analyzes the ported address to determine whether the ported address is a text address  114 . If the ported address is a text address, then the NPDB queries a directory name server to request the IP address which corresponds to the text address. 
     The NPDB then returns  115  the IP address to which the called subscriber is ported to the originating MSC/end user terminal/network node via the “Routing IP Address” parameter ( 119 , FIG.  6 ). The NPDB additionally returns  120  the available protocol options of the ported gateway via the “Ported Gateway Capabilities” parameter. The originating domain (i.e., the mobile switching center, end user terminal, or network node), then selects  122  one of the options specified in the parameter for initiating  123  the call towards the ported domain (or the new service provider). 
     Thus, as described above, exemplary embodiments of the invention extend the number portability principle, implemented in existing telecommunication networks, to support IP address portability between telecommunication service providers and data communication service providers or between data communication service providers and other data communication service providers. One skilled in the art will additionally recognize that a number of standard protocols could be used to support the enhancements of the exemplary embodiments of the invention described above with only minor modifications. For telecommunications domains, these protocols could include, e.g., ANSI41, GSM MAP, and ISUP (ISDN user part). For data communications domains these protocols could include, e.g., SIP and H.323. 
     Although a number of embodiments are described herein for purposes of illustration, these embodiments are not meant to be limiting. Those skilled in the art will recognize modifications that can be made in the illustrated embodiments. Such modifications are meant to be covered by the spirit and scope of the appended claims.