Background and Related Art Currently, wireless subscriber profile data is configured in a home location register (HLR). The HLR resides either on a computing module (CM) which is an end office telephony switch or in an off-board node that supports IS-41 protocol signaling. The subscriber data profile is retrieved from the HLR upon registration and stored in a visitor location register (VLR) while the subscriber is actively roaming. By contrast, wireline subscriber profile data, which includes internet (IP) telephones, is stored within the computing module in the form of table data. Wireline subscribers currently do not have public switching telephone network (PSTN) roaming capability.

The present invention addresses several shortcomings of the current configuration. First, the current subscriber profile data in the computing module does not provide the ability to map E. 164 telephone directory numbers into internet addresses, e-mail addresses or universal resource locators (URLs) as may be used by IP telephones. Second, current systems have no provision

for wireline mobility because an assumption is made that the address of a wireline is fixed, tied to a physica interface, and only moved by changes to the provisioned tables.

Summarv of the Invention As with standard wireline telephony subscribers, IP telephony subscribers are assigned a standard ten (10) digit E. 164 directory number (hereinafter"directory number") comprised of a three (3) digit area code, a three (3) digit exchange within the area code, and a four (4) digit unique extension within the exchange. When a call is incoming to the central office of a subscriber's home service area which supports computer network telephony, such as for instance IP telephony, a signaling control point translates the directory number into an IP address, URL address, or electronic mail address much the same that a local number portability node re-routes calls for non-IP telephony systems. The signaling control point is signaled from an advanced intelligent network (AIN) termination attempt trigger point and provides the directory number of an H. 323 gateway and the IP address of the subscriber's H. 323 IP telephony end point. If the subscriber has de-registered from the signaling control point, an overflow route to a land line or voice mail is provided.

Local number routing (LNR) fields are re-used with the local number becoming the ten (10) digit directory number of the gateway, and the called directory number (CDN) becoming the IP address, or a new transmission

control application protocol (TCAP) field could be introduced specifically for the IP address.

When a subscriber is roaming in another network, the roamed into (visited) gateway signals back to the home location register/signaling control point of the subscriber's network and registers its (i. e., the visited gateway's) public switching telephone network telephone directory number and the IP address assigned to the subscriber while connected to the visited network.

When subsequent calls are incoming to the subscriber's home network switch, the home location register/signaling control point provides the ten (10) digit directory number of the visited gateway and the new IP address rather than the home gateway telephone number and IP address of the subscriber.

This provides the subscriber with a virtual private network for placing telephone calls over IP terminals. Thus, subscribers have the ability to roam amcng networks and continue placing or receiving telephone calls ubiquitously.

The subscriber maintains a single telephone directory number and receives service no matter which IP network he is currently connected to. Under the present invention, subscribers can, for instance, move from a static network connection at work to a dial in network connection from home.

The present invention provides a method of managing call origination for subscribers on a packet data telephony network which includes a home location register. A subscriber registers a packet data communication (IP telephony) device with the home location register of the subscriber's home packet data (IP) network, and uses the home location register to translate the

subscriber's packet data (IP) address into a (E. 164) telephone directory number.

The present invention also provides a method of managing call termination (i. e., call reception) for subscribers on a packet data telephony network which includes a home location register. The subscriber registers a packet data communication (IP telephony) device with the home location register of the subscriber's home packet data (IP) network, and uses the home location register to translate the subscriber's (E. 164) telephone directory number into a packet data (IP) address.

The present invention further provides a method of public switching telephone network based roaming call origination for lP telephony devices.

The subscriber registers his IP telephony device on a remote IP network, and may originate calls from the IP telephony device on the remote network to a third party.

The present invention still further provides a method of public switching telephone network based roaming call termination (i. e., call reception) for IP telephony devices. An IP subscriber registers his IP telephony device on a remote IP network, and may receive calls on the IP telephony device on the remote network from a third party.

It is therefore an object of the invention to provide PSTN based network roaming for IP telephony devices.

It is a further object of the invention to provide SCP based management for IP telephony devices.

Some of the objects of the invention having been stated hereinabove, other objects will become evident as the description proceeds, when taken in connection with the accompanying drawings as best described hereinbelow.

Brief Description of the Drawings FIGURE 1 is a block diagram illustrating the hardware nodes present in a subscriber's home area network and a link to outside networks; FIGURE 2 is a block diagram illustrating the hardware nodes required for roaming on a public network; FIGURE 3 is a block diagram illustrating the hardware nodes required for roaming on a private network.

FIGURE 4 illustrates the method or process steps for subscriber registration within the home area network; FIGURE 5 illustrates the method or process steps for call origination for a subscriber within the home area network; FIGURE 6 illustrates the method or process steps for call termination within the home area network; FIGURE 7 illustrates the method or process steps for subscriber registration while roaming on a remote area network; FIGURE 8 illustrates the method or process steps for call origination while roaming on a remote area network; and FIGURE 9 illustrates the method or process steps for call termination while roaming on a remote area network.

Detailed Description Referring now to FIGURES 1-3, a packet data telephony network is shown in each figure. In figures 2 and 3, two (2) packet data telephony networks are shown linked together by a public switching network and a virtual private network, respectively. It is to be understood that multiple (more than two) packet data telephony networks may be linked together. Each network has a number of common elements which include home location registers (HLR) 40, visitor location registers (VLR) 120, gatekeepers (GK) 30,110, gateways (COGW) 50,130, central offices (CO) 60,140, and various packet data telephony devices 10,25,35. Other devices may be connected to the packet data network without departing from the spirit or scope of the present invention.

FIGURE 1 illustrates a home switch call scenario. Registration, call origination, and call termination functions are described for a subscriber utilizing his home network. Registration refers to the process of provisioning the home location register (or the visitor location register if roaming) with the subscriber's relevant data. Call origination refers to placing a call while call termination refers to receiving a call.

Registration is initiated when a subscriber logs into his computer at work.' Once the subscriber connects his IP telephone 10 to his home IP network 20, registration is initiated with a local serving gatekeeper (GK) 30. Gatekeeper 30 forwards the registration information to a serving home location register (HLR) 40 which validates the subscriber. Home location register 40 responds with authentication data and subscriber profile data which is then stored within

gatekeeper 30. Home location register 40 stores the directory number (DN) of the central office gateway (COGW) 50, the directory number of the subscriber, and the assigned IP address of the subscriber's IP telephone 10.

Consider a situation in which the subscriber wishes to initiate a call to someone who lives in a different service area. The subscriber's gatekeeper 30 queries his home location register 40 supplying his IP address. Home location register 40 supplies the subscriber's directory number, authentication data and any other data needed to place the call. The subscriber's gatekeeper 30 initiates a call origination via the central office gateway 50 and central office (CO) 60 by supplying the subscriber's directory number as the calling party and called party's directory number. The call routes normally over a public switching telephone network (PSTN) 70 to the called party's serving central office 80.

Now consider the reverse situation in which someone wishes to initiate a call to the subscriber (e. g., call termination). The caller 90 dials the subscriber's telephone directory number. The call routes normally over the public switching telephone network 70 from the caller's central office 80 to the subscriber's central office 60. The subscriber's central office 60 queries home location register 40 by supplying the subscriber's directory number and retrieves the directory number of the subscriber's central office gateway 50 and the IP address of the subscriber's IP phone 10. The subscriber's central office 60 routes the call to the subscriber's central office gateway 50 by supplying the ! P address of the subscriber's IP phone 10. Lastly, the subscriber's central office gateway 50 uses the subscriber's IP address to route the call to the

subscriber's IP telephone 10. Call origination may be optimized by duplicating the IP address to directory number mapping in the gatekeeper.

FIGURE 2 illustrates the architecture necessary to place and receive calls while roaming on a public network. Consider a scenario where a subscriber is out of his home service area. The subscriber registers on a remote network by connecting to the remote network 100 and initiating contact with the remote network's gatekeeper 110 in which the subscriber supplies his home area directory number. The remote gatekeeper 110 receives the registration request and recognizes it as a non-local subscriber based on the supplied directory number. The remote gatekeeper 110 then forwards the request to a visitor location register (VLR) 120 which will validate the subscriber if his subscriber profile is already resident on remote visitor location register 120. If the subscriber's profile is not yet resident on remote visitor location register 120, then visitor location register 120 initiates a registration request to the subscriber's home location register 40 using the subscriber's supplied directory number and/or a system ID to locate home location register 40. The subscriber's home location register 40 responds by forwarding his subscriber profile and authentication data. Remote visitor location register 120 stores the subscriber's home directory number, his assigned remote network IP address, and the directory number of the remote network central office gateway 130.

The subscriber's home location register 40, in turn, stores the remote network's 100 central office gateway 130 directory number and/or IP address. Next, remote visitor location register 120 responds to remote gatekeeper 110 with the subscriber's profile and authentication information which is stored in remote

gatekeeper 110. Where possible, standard IS-41 or GSM-MAPprotocois are used for communications among home location register nodes, visitor location register nodes, and gatekeeper nodes. The gatekeepers act as mobile switching centers (MSCs) with respect to IS-41 or GSM-MAP protocols.

Call origination for a public network roaming call scenario is performed as follows. When the subscriber wishes to call someone while roaming on a remote network, he dials the called party's directory number. The remote gatekeeper 110, recognizing that the subscriber's IP address is dynamically assigned, queries remote visitor location register 120 supplying the subscriber's assigned IP address. Remote visitor location register 120 sends back the subscriber's home directory number as well as authentication data needed to place the call. Remote gatekeeper 110 initiates an origination via remote central office gateway 130 and central office 140 by supplying the subscriber's home directory number as the calling party and the called party's directory number. The call routes normally over public switching telephone network 70 to the called party's central office 80. Call origination may be optimized by duplicating the IP address to directory number mapping in the gatekeeper.

Call termination for a public network roaming call scenario is performed as follows. This time, the subscriber receives a call from someone while he is roaming in another network. The caller dia ! s the subscriber's telephone directory number. The cail routes normally over public switching telephone network 70 from the caller's serving central office 80 to the subscriber's home central office 60. The subscriber's central office 60 queries its home location register 40 by supplying the subscriber's directory number. Home location

register 40 returns the directory number of the central office gateway 130 of the network 100 in which the subscriber is roaming. The subscriber's home central office 60 routes the cail to the remote network central office 140 using the remote central office gateway 130 directory number and supplying the subscriber's home directory number and/or URL or electronic mail address. If the directory number only is supplied, remote central office 140 queries remote visitor location register 120 by supplying the subscriber's home directory number and retrieves the subscriber's remote assigned IP address. Remote central office 140 routes the call to remote centrai office gateway 130 by supplying the subscriber's dynamically assigned IP address. Lastly, remote central office gateway 130 uses the subscriber's IP address to route the call to the subscriber.

Private network roaming, illustrated in FIGURE 3, is achieved in almost identical fashion as public network roaming with the following exceptions. IS- 41/GSM-MAP messages can be sent over a virtual private network (VPN) 160 instead of the IS-41 or GSM-MAP public network 150, thereby lowering costs.

Second, the local gatekeeper can make least cost routing and/or quality of service decisions and choose to route a call over a public switching telephone network or a virtual private network.

FIGURES 4-9 illustrate method or process steps for various functions of the present invention. It is to be understood that each of the method or process steps illustrated herein are readily implementable by those of ordinary skill in the art as a computer program product having a medium with a computer program embodied thereon. The computer program product is

capable of being loaded and executed on the appropriate computer processing device (s) in order to carry out the method or process steps described.

FIGURE 4 illustrates the method or process steps for subscriber registration within the home area network. Once a subscriber connects 402 his IP telephone to his home IP network, registration is initiated and an IP address is assigned 404 to the IP phone. A registration initiation message is sent 406 to the IP network gatekeeper. The gatekeeper forwards 408 the registration information to the serving home location register (HLR) which validates the subscriber's service and authentication data. The home location register responds 410 with authentication data and subscriber profile data. At this point, the authentication data and subscriber profile data can be stored within the gatekeeper 412 or the network gateway directory number, IP phone directory number, and assigned IP address can be stored in the home location register 414.

FIGURE 5 illustrates the method or process steps for call origination for a subscriber within the home area network. Once a subscriber has registered his IP telephony device with his home area IP network, he may place or receive calls. To place a calf (calf origination), the subscriber dials and the gatekeeper sends 502 the IP address previously assigned during registration to the home location register. The home location register returns 504 the subscriber's directory number, authentication data and any other data needed to place the call to the gatekeeper. The subscriber's gatekeeper then originates 506 the call origination by supplying the subscriber's directory number as the calling party and called party's directory number to the central office gateway and

central office (CO). The call routes 508 normally over a public switching telephone network (PSTN) to the calied party's serving central office.

FIGURE 6 iliustrates the method or process steps for call termination within the home area network. A caller dials the subscriber's telephone directory number. The call routes normally over the public switching telephone network from the caller's central office to the subscriber's central office 602.

To retrieve the call (call termination), the subscriber's central office queries 604 home location register by supplying the subscriber's directory number and retrieves 606 the directory number of the subscriber's central office gateway and the IP address of the subscriber's IP phone. The subscriber's central office routes 608 the call to the subscriber's central office gateway by supplying the IP address of the subscriber's IP phone Lastly, the subscriber's central office gateway uses the subscriber's IP address to route 610 the call to the subscriber's IP telephone.

FIGURE 7 illustrates the method or process steps for subscriber registration while roaming on a remote area network. The subscriber initiates registration on a remote IP network by connecting 702 his IP phone to the remote IP network. The remote IP network initiates 704 contact via a registration request message with its gatekeeper in which the subscriber supplies his home area directory number. The remote gatekeeper receives the registration request and recognizes it as a non-local subscriber based on the supplied directory number. The remote gatekeeper then forwards 706 the request to a visitor location register (VLR). If the subscriber's profile is not yet resident on remote visitor location register then visitor location register initiates

708 a registration request to the subscriber's home location register using the subscriber's supplied directory number and/or a system ID to locate home location register. The subscriber's home location register responds 710 by forwarding his subscriber profile and authentication data. Remote visitor location register stores 712 the subscriber's home directory number, his assigned remote network IP address, and the directory number of the remote network central office gateway. The subscriber's home location register in turn, stores 714 the remote network's central office gateway directory number and/or IP address. Next, remote visitor location register responds 716 to remote gatekeeper with the subscriber's profile and authentication information which is stored 718 in the remote gatekeeper.

Otherwise, the visitor location register will validate 720 the subscriber since his subscriber profile is already resident on remote visitor location register. The visitor location register sends 722 the service profile and authentication data to the remote IP network gatekeeper where it is then stored 724.

FIGURE 8 illustrates the method or process steps for call origination while roaming on a remote area network. When the subscriber wishes to call someone while roaming on a remote network, he dials the called party's directory number. The remote gatekeeper recognizing that the subscriber's IP address is dynamically assigned, queries 802 remote visitor location register supplying the subscriber's assigned IP address. Remote visitor location register sends 804 back the subscriber's home directory number as well as authentication data needed to place the call. Remote gatekeeper initiates 806

an origination via remote central office gateway and central office by supplying the subscriber's home directory number as the calling party and the called party's directory number. The call routes 808 normally over public switching telephone network to the called party's central office.

FIGURE 9 illustrates the method or process steps for call termination while roaming on a remote area network. A caller dials the subscriber's telephone directory number. The call routes normally over public switching telephone network from the caller's serving central office to the subscriber's home central office 902. The subscriber's central office queries its home location register by supplying the subscriber's directory number. Home location register returns 904 the directory number of the central office gateway of the network in which the subscriber is roaming. The subscriber's home central office gateway routes 906 the call to the remote network central office gateway using the remote central office gateway directory number and supplying the subscriber's home directory number and/or URL or electronic mail address. If the directory number only is supplied, remote central office queries 908 remote visitor location register by supplying the subscriber's home directory number and retrieves 910 the subscriber's remote assigned IP address. Remote central office routes 912 the call to the subscriber via remote central office gateway by supplying the subscriber's dynamically assigned IP address.

Alternatively, the call can be routed 914 from the home network gateway to the remote network gateway using the IP address of the subscriber's IP phone rather than using the subscriber's directory number. Remote central

office would then routes 916 the call to the subscriber via remote central office gateway by supplying the subscriber's dynamically assigned IP address.

Appropriate computer program code in combination with hardware implements many of the elements of the present invention. This computer code is often stored on storage media. This media can be a diskette, hard disk, CD-ROM, or tape. The media can also be a memory storage device or collection of memory storage devices such as read-only memory (ROM) or random access memory (RAM). Additionally, the computer program code can be transferred to the appropriate hardware over some type of data network.

It is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims.

For instance, an ATM or other packet data network may be substituted for the IP network used throughout the foregoing description.

Further, E. 164 directory numbers to an IP address is only one mapping that the present invention contemplates. Universal resource locator (URL) addresses, electronic mail addresses, etc... may be substituted for the IP address mapping.

Still further, gateway protocols are freely substitutable. The present invention has been described using the H. 323 protocol. Other protocols, including, but not limited to, internet protocol device control (IPDC), simple gateway control protocol (SGCP), and session initiation protocol (SIP) may also be implemented.

The invention is defined by the following claims, with equivalents of the claims to be included therein.