[0001] The present invention claims the benefit of U.S. Provisional Patent Application S. No. 60/455,353, filed Mar. 17, 2003 titled “Methods and Apparatus For Supporting IP Telephony” and is a continuation-in-part of U.S. utility patent application Ser. No. 10/337,106, filed on Jan. 6, 2003 titled “Methods And Apparatus For Determining The Port And/Or Physical Location Of An IP Device And For Using That Information” which claims the benefit of U.S. Provisional Patent Application S. No. 60/346,596, filed Jan. 8, 2002 titled “Methods And Apparatus For Determining The Port And/Or Physical Location Of An IP Device And For Using That Information” each of which is hereby expressly incorporated by reference.
[0002] The present invention is directed to communications systems and, more particularly, to methods and apparatus for integrating IP-based telephone users into known emergency telephone services, e.g., 911.
[0003] Digital communications networks have continued to grow in importance as people have come to rely on the electronic exchange of information to support both business and personal pursuits. E-mail, the electronic transfer of files, and various other services are made possible by the use of digital communications networks.
[0004] The type of digital communications network employed often depends on the size of the network to be implemented, as well as the needs and capabilities of the party or parties implementing the network. Hardware cost and network management complexity are often a factor when choosing the type of network to be implemented.
[0005] Networks limited to a small geographical region, e.g., home or single office location, are frequently called local area networks (“LANs”). LANs are often privately-owned networks within a single building or small campus. LANS are widely used to connect personal computers and workstations at a single location, e.g., company office or residence, to one another and to shared resources such as printers and/or local centralized file storage.
[0006] One popular type of LAN, an IEEE 802.3 standard based LAN is popularly called Ethernet. Ethernet is a bus based broadcast network with decentralized control. When using Ethernet, data, e.g., messages, information and signals are transmitted in Ethernet using frames. Ethernet devices broadcast and receive frames over the shared bus over which the frames are broadcast. The format of an IEEE 802.3 frame
[0007] Six byte global Media Access Control (MAC) Ethernet device addresses are assigned by a central authority to ensure that no two stations on the same Layer
[0008] Since Ethernet MAC address are unique at least on the same Layer 2 network, and potentially globally, any device on a Layer 2 network can address any other device on the network by just using the right 48 bit MAC address assigned to the device being addressed.
[0009] MAC addresses are data link layer addresses. The data link layer corresponds to the second layer of the seven layer OSI (Open Systems Interconnection) Reference Model. As a result, Ethernet LANs and other LANS which use data link layer addresses are sometimes called Layer 2 networks.
[0010] In addition to the address information
[0011] While Layer 2 networks are well suited for implementing LANs, e.g., at relatively small sites, it is often desirable to connect devices, e.g., computers located on different LANs. Layer 3 networks, which rely on network protocols, e.g. TCP/IP protocols, are often used for interconnecting Layer 2 networks. Layer 3 packets, e.g., IP packets, are often encapsulated in Layer 2 frames to extend the reach of the Layer 3 network to host devices on the Layer 2 network. This permits Layer 2 signaling and frames to be used for transmissions of data over the Ethernet while preserving Layer 3 addressing information for transmission over the Layer 3 network. The network resulting from interconnecting one or more Layer 2 and Layer 3 networks is often referred to as an internet.
[0012] The Internet is a well-known worldwide internet that is used to connect computers and other devices located at universities, governments offices, businesses and individuals together.
[0013]
[0014] In the
[0015] Routers, serve as forwarding devices and, optionally, protocol conversion devices. In the
[0016] Routers
[0017] Unlike LANs which use data link layer addresses, the Internet uses Layer 3 (Network layer) addresses, e.g., IP Addresses, for purposes of identifying source and destination devices and determining the appropriate route upon which packets should be transmitted. Source and destination IP addresses are included, along with data, in IP packets used to transmit information across the Internet. Every host and router on the Internet has an IP address which encodes its IP network number and host number. The combination is unique, no two machines have the same IP address.
[0018] Exemplary IP addresses are 32 bits long and are used in the Source address and Destination address fields of IP packets.
[0019] The demand for IP address continues to grow and, with fewer bits than are used for MAC addresses, there are considerably fewer IP addresses available for allocation. Given the demand for IP addresses and the limited supply, IP addresses are leased from a central authority responsible for overseeing their allocation. Internet service providers, may lease a large number, e.g., a block of IP addresses, which the provider then sub-leases to end users, e.g., host devices.
[0020] As a result of the lease (actually the sub-lease) process, end users obtain an IP address which is subject to lease restrictions including the right to use the IP address for a limited period of time. IP addresses leased for extended periods of time, e.g., a year or more, are often termed “static” IP addresses. Static IP addresses are used for applications such as Web site hosting where the Internet connection is likely to remain active and in use for extended periods of time. Users normally pay a premium for static IP addresses.
[0021] With regard to individual Internet users, IP addresses are more commonly leased to end users on a dynamic basis. Internet service providers frequently use a DHCP server to assign users IP addresses for a limited lease time when they seek to access the Internet, e.g., from a host device coupled to the Internet by way of a Layer 2 network.
[0022] Once an IP address is leased to a host, e.g., user, if the host remains active beyond the lease term, the lease may be extended or a new IP address assigned to the host from the available pool of IP addresses at the end of the first lease term.
[0023] When a user intends to stop using the IP address, the user's device, e.g., host device
[0024] Thus, unlike MAC address which are fixed for the life of a product by the manufacturer, the IP address assigned to a particular host device can change from moment to moment. Accordingly, in contrast to MAC addresses which are fixed for the life of a product by the manufacturer, there is no permanent fixed relationship between a physical device and the IP address assigned to the device.
[0025] Many contemplated IP applications could benefit from reliable information about the location and/or identity of a host device using an IP address. The dynamic allocation of IP addresses and re-use of IP addresses discussed above, greatly complicates attempts to accurately correlate specific devices and/or physical locations with an IP address.
[0026] The problem of associating IP addresses with physical locations is further complicated by the manner in which IP addresses are assigned and used. Blocks of IP addresses are assigned by the central authority to different network providers based on the size of their networks. Unlike zip codes or telephone number area codes, assignment of IP addresses is independent of geographic location. Accordingly, IP addresses do not inherently convey geographic location information as do, for example, zip codes used by the post office or the area code portion of a telephone number.
[0027] Reliable location information is also difficult to obtain in an IP network because IP based routing relies, in most cases, on the intelligence of the network to determine the routing path to a specified destination address. The host need not, and in most cases does not, know the physical location of the destination device to which it is sending packets or the route over which the transmitted packets will be conveyed. In addition, routers in an IP network usually only need to determine the next router in a path based on an IP address and therefore often do not include detailed topology information relating to large portions of an IP network. While shielding end devices and routers from having to make end to end routing decisions has many advantages, the lack of information about the physical devices corresponding to IP addresses poses problems in many contemplated IP based applications.
[0028] IP based services, those based on private internets and the larger Internet are continuing to grow in importance. IP and the Internet are beginning to be used for a wide range of applications such as music file sharing, news delivery, software distribution, etc. IP and Internet applications which are expected to grow in importance in the future include Internet telephony and video on demand services. In the case of Internet telephony voice signals are exchanged over the Internet through the use of packets including voice data. In the case of video on demand (VoD) services, video in the form of digital files transmitted as packets, is supplied to a customer using the Internet as the transport mechanism.
[0029] In many cases, it would be useful if the physical location of a device using an IP address could be determined from its IP address. One particularly relevant and important application where IP device location is important is the servicing of IP telephony calls by emergency service call centers such as 911 call centers.
[0030] Unfortunately, there is currently no simple way to convey physical location information to a
[0031] In the case of existing 911 service for landline phones, calling party telephone number information is forwarded over the PSTN to a 911 emergency call center as part of the standard automatic number identification information provided as part of standard SS7 signaling associated with a telephone call. The emergency call center uses the calling party's telephone number to access a 911 database which correlates telephone numbers to physical locations, e.g., the address of the telephone service subscriber to which the telephone number is assigned. Entries in the 911 telephone number/location database are updated infrequently, e.g., usually with the assignment or reassignment of a landline telephone number. Usually the information for a specific telephone number is entered at the time the telephone number is assigned and frequently remains unmodified until telephone service for the particular number is discontinued. Currently there is no easy way to frequently update the contents of the existing 911 location information databases to reflect a phone, e.g., an IP phone, being moved from location to location.
[0032] In view of the above discussion, there is a need for methods and apparatus for providing calling party location information to an emergency 911 service center when the center is servicing a call associated with an IP telephony device. It is desirable that such location information can be provided in a way that avoids the need to make significant or costly modifications to current 911 location information database systems or to add significant amounts of hardware to such systems. From the emergency service center perspective, it would be ideal if accurate location information could be obtained regardless of whether a call is placed from an IP telephony device or a landline phone in the same manner that location information is currently retrieved for landline calls.
[0033] The present invention is directed to methods and apparatus for providing location information to an emergency call center, e.g., a 911 call center, for calls placed from IP telephony devices.
[0034] In accordance with the invention IP phones register with an IP switch, e.g., a soft switch, which has access to stored information associating the IP phone's telephone number with an IP address. The IP address assigned to a phone may vary at any specific point in time, e.g., depending on factors including which router port is used to couple the phone to the IP network. Since IP addresses can be assigned dynamically, each time an IP phone is reconnected to the IP network, the IP telephony device updates the IP address information associated with its assigned telephone. Calls to/from an IP telephone are then directed based on the updated IP address information maintained by the soft switch.
[0035] As a result of the soft switch registration process calls to an IP telephone number may be routed from/to different locations at different times depending on the physical location of an IP telephony device. Accordingly, an IP phone number, unlike a landline number, normally does not have a fixed physical location associated with it and therefore does not provide accurate location information since the phone number is not tied to a specific location.
[0036] In accordance with the present invention, for purposes of servicing emergency calls, e.g., for E-911 purposes, a telephone number is associated with each edge router port associated with a specific location, e.g., office, residence, etc., that may be used to support an IP telephone. A telephone number associated with the edge router port and the corresponding location information is stored in an emergency location information database, e.g., an existing database used for providing 911 calling party location information for calls from landline phones. The telephone number may be, e.g., the number of a landline phone located at a customer premise location to which the edge router port is connected or a telephone number which is not actually used to provide telephone services but is used, in accordance with the present invention, as a way of conveying location information. Normally the telephone number associated with the edge router port will be different than the telephone number associated with an IP phone for purposes of routing calls to the IP phone.
[0037] When the soft switch of the present invention used for routing IP calls detects a telephone call to an emergency call center, e.g., a 911 call, it determines the edge router port from which the call was made.
[0038] This can be done using the IP address associated with the calling party's IP telephone and the techniques discussed below. Once the edge router port is identified, the soft switch performs a look-up operation to determine the telephone number associated with the port for emergency call purposes. This telephone number may correspond to a telephone which is not registered to the IP caller. In fact, it may even correspond to a telephone number which is not even in active use for placing and/receiving calls. Significantly, however, the telephone number associated with the utilized edge router port corresponds to the location from which the IP telephony call is placed, e.g., the location of the customer premise corresponding to the edge router port through which the IP call was received.
[0039] The IP based call to the emergency call center, referred to herein for purposes of explanation as a 911 call, is routed to PSTN by an IP to PSTN gateway with the telephone number retrieved from the look-up operation being supplied as the calling party number instead of the actual calling party number. Upon receiving the 911 call, the 911 service center performs an address look-up operation using the supplied calling party number in the normal manner. This results in the address associated with the port from which the IP-based call was placed being supplied to the 911 operator along with the voice portion of the IP telephone call. This calling party number can be used to determine the physical location of the calling party.
[0040] Significantly, hardware modifications to existing emergency location information databases which associate telephone numbers with customer premise locations are not required to implement the present invention. The location information databases merely need to be loaded with telephone numbers, and corresponding physical customer premise location information, that are associated in accordance with the present invention with edge router ports used to provide IP telephony service. Such telephone number and address information may be loaded into the 911 database at the time IP service is initially provisioned for a customer premise and left unchanged until service to the customer premise through the port is terminated. Thus, updates to the emergency location information database corresponding to individual customer premises through which IP telephone service may be provided can be relatively infrequent, e.g., the same or about as frequent as the data base is updated in regard to landline phones.
[0041] Accordingly, without requiring modifications to the existing PSTN portion of the 911 system, emergency service telephone operators can be supplied with location information for IP based calls. This information can then be used, e.g., to dispatch emergency services to the source of the call to the 911 telephone call.
[0042] Numerous additional embodiments, features and applications for the methods and apparatus of the present invention are discussed in the detailed description that follows.
[0043]
[0044]
[0045]
[0046]
[0047]
[0048]
[0049] FIGS.
[0050]
[0051]
[0052]
[0053]
[0054]
[0055]
[0056]
[0057]
[0058] The system illustrated in
[0059] The first Layer 2 network, e.g., LAN
[0060] An IP based network
[0061] The first and second edge routers
[0062] The DHCP server
[0063] To facilitate the secure exchange of customer and management information between system components, e.g., routers and servers in the system
[0064] As an alternative to using a separate network for the exchange of management and customer information, secure communications channels can be implemented between system components, e.g., routers and servers, using encryption and/or other virtual private networking techniques. Accordingly, customer and management may be transmitted over separate physical communications channels or secure communications channels provided using existing communications links between network elements.
[0065] Various elements are incorporated into the SMN
[0066] For various applications, e.g., servicing of 911 emergency telephone calls, the SS
[0067] An emergency call center, e.g., a 911 operator center
[0068] The exemplary communication system
[0069] In accordance with the present invention, the location information database
[0070] The memory
[0071] The Layer 2 forwarding table
[0072]
[0073] The Layer 3 (L3) forwarding table
[0074] The L2 to L3 address resolution table
[0075] When an IP packet is received which has a destination address not found in the L3 forwarding table
[0076] In accordance with one feature of the invention, as an alternative to using address resolution protocol (ARP), the DHCP monitoring routine
[0077] Address resolution table management routine
[0078] Port number information routine
[0079] The routine
[0080] The router port number determined by port number information routine
[0081]
[0082] When a device on a LAN, e.g., device
[0083] This may be done as is known in the art using DHCP protocol. An IP address assignment request conveyed to the DHCP server
[0084] Each entry
[0085] When an IP address is assigned, i.e., leased, to a requesting device, the IP address and lease time information (indicating the duration of the lease) is communicated back to the requesting device by way of the edge router acting as the device's proxy.
[0086] Accordingly, as part of the DHCP server IP address leasing mechanism, a table
[0087] Edge router information requests, e.g., requests from the LCIS
[0088]
[0089] The LCIS
[0090] The memory
[0091] The IP address to DHCP server database
[0092] The RPC database
[0093]
[0094] The information request response routine (IRR)
[0095] An exemplary IRR routine
[0096] In step
[0097] In step
[0098] In response to the port information request message, in step
[0099] Once the desired information, e.g., customer name, location, telephone number is retrieved from the RPLC database, in step
[0100] Once the requested information corresponding to the IPAOI has been transmitted to the requesting device, e.g., over the secure SMN
[0101] The soft switch
[0102]
[0103] As illustrated in
[0104] CPU
[0105] The soft switch's PSTN gateway
[0106] The soft switch's memory
[0107] As discussed earlier, each device coupled to the Ethernet, e.g. device
[0108] After authentication, the registration/management routine
[0109] Using the active device information stored in table
[0110] Call processing routine
[0111] In one exemplary embodiment, when a user enters a telephone number on an IP phone, e.g., to place a call, the IP phone is connected to a local soft switch
[0112] Soft switch
[0113] As part of normal call routing procedure, the call processing routine
[0114] Thus, soft switch E911 routine
[0115]
[0116] The telephone number of the IP telephony device may, and in one embodiment is, inserted by the soft switch into an SS7 signal field used to indicate a telephone from which a call is forwarded for IP telephony calls directed to an emergency call service center. In such an embodiment the service center is provided with the telephone number of the IP telephony device used to place the call in addition to the non-routing telephone number to be used for location determination purposes. Since, in some embodiments, the service center can determine from the format or value of the non-routing telephone number that it is a number which is not to be used for contact purposes, in such cases the operator can default to using the telephone number included in the call forwarding indicator field of the SS7 call to determine a telephone number which can be used to contact the calling party.
[0117] While shown as part of the service center
[0118] Working at an operator workstation
[0119] The steps of an exemplary soft switch E911 routine
[0120] In step
[0121] In step
[0122] In step
[0123] When the 911 call is received at the 911 operator center
[0124] It is to be understood that numerous variations on the above described methods and apparatus are possible without departing from the scope of the invention.
