Case 6:20-cv-00272-ADA Document 65-19 Filed 03/14/22 Page 1 of 25
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`Exhibit 17
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`Case 6:20-cv-00272-ADA Document 65-19 Filed 03/14/22 Page 2 of 25
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`(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`1111111111111111 IIIIII IIIII IIII I II Ill lllll 111111111111111111111111111111 IIII IIII
`
`(43) International Publication Date
`22 November 2001 (22.11.2001)
`
`PCT
`
`(10) International Publication Number
`WO 01/89145 A2
`
`(51) International Patent Classification 7:
`
`H04L 12/00
`
`(21) International Application Number:
`
`PCT/SE0l/00972
`
`(22) International Filing Date:
`
`4 May 2001 (04.05.2001)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(30) Priority Data:
`09/570,997
`
`15 May 2000 (15.05.2000) US
`
`(71) Applicant: TELEFONAKTIEBOLAGET LM ERICS-
`SON (PUBL) [SE/SE]; S-126 25 Stockholm (SE).
`
`(72) Inventor: FOTI, Georges; 163 Mozart, Dollard des
`Ormeaux, Quebec H9G 2Z8 (CA).
`
`(81) Designated States (national): AE, AG, AL, AM, AT, AU,
`AZ, BA, BB, BG, BR, BY, BZ, CA, CH, CN, CO, CR, CU,
`CZ, DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM,
`HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK,
`LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX,
`MZ, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL,
`TJ, TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW.
`
`(84) Designated States (regional): ARIPO patent (GH, GM,
`KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), Eurasian
`patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), European
`patent (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE,
`IT, LU, MC, NL, PT, SE, TR), OAPI patent (BF, BJ, CF,
`CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG).
`
`Published:
`without international search report and to be republished
`upon receipt of that report
`
`(74) Agent: MAGNUSSON, Monica; Ericsson Radio Systems
`AB, Patent Unit Radio Access, S-164 80 Stockholm (SE).
`
`For two-letter codes and other abbreviations, refer to the "Guid(cid:173)
`ance Notes on Codes and Abbreviations" appearing at the begin(cid:173)
`ning of each regular issue of the PCT Gazette.
`
`----iiiiiiii
`iiiiiiii ---
`-!!!!!!!!
`--iiiiiiii
`iiiiiiii ----
`< (54) Title: METHOD OF MONITORING CALLS IN AN INTERNET PROTOCOL (IP)-BASED NETWORK
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`iiiiiiii
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`I.I) (57) Abstract: A method of monitoring a call with a mobile terminal (MT) (11) in an Internet Protocol (IP)-based network (10)
`~ having a Gatekeeper (17) that controls the network, a plurality of access routers (12, 14) that provide access to the network, and a
`~ Monitoring Station (18) having monitoring facilities and a database of MTs to be monitored. When the MT sends an Admission
`Q0 Request message (21) to the Gatekeeper, the Gatekeeper sends a query (23) to the Monitoring Station asking whether the MT is to
`-.... be monitored. The Monitoring Station sends a reply (25) to the Gatekeeper indicating that the MT is to be monitored and providing
`
`router (12) associated with the MT. The request identifies the MT to be monitored, instructs the access router to monitor the MT, and
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`S an IP address where monitored packets are to be sent. The Gatekeeper then sends a monitoring request message (28) to the access
`0 provides a unique call identification (Call ID) and the IP address where monitored packets are to be sent. When the access router
`> detects a packet associated with the MT, the router sends all packets associated with the MT to the Monitoring Station. The method
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`;;, also controls monitoring during intra-domain and inter-domain handoffs of the MT.
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`WO 01/89145
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`METHOD OF MONITORING CALLS
`IN AN INTERNET PROTOCOL (IP)-BASED NETWORK
`
`BACKGROUND OF THE INVENTION
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`5
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`Technical Field of the illVention
`
`This invention relates to telecommunication systems and, more particularly,
`to a method of monitoring calls in an illtemet Protocol (IP)-based network.
`Description of Related Art
`
`ill existing circuit-switched telecommunications networks such as the Public
`
`Switched Telephone Network (PSTN) and the legacy Public Land Mobile Network
`(PLMN), law enforcement agencies are able to easily monitor telephone calls because
`the calls, once established, are routed over a dedicated path from one subscriber to
`
`another. ill an IP-based telecommunications network, this is not the case.
`
`For IP calls that originate in a circuit-switched network, a gateway provides an
`interface between the circuit-switched network and the packet-switched IP network.
`The gateway takes bits of digitized voice, packetizes them, puts on a header, and ships
`them over the IP network. The packetized call may enter the core IP network at any
`access (edge) router near the originating subscriber. Thereafter, the individual packets
`follow any available route to the destination address. At that point, all of the packets
`exit the core network through a single access router near the destination subscriber.
`The same principle applies if both the calling terminal and the called terminal are IP(cid:173)
`
`based. Since one or both of the subscribers involved in the call may be mobile, calls
`between the same subscribers may enter and leave the IP network through different
`access routers at different times. As a result of the changing access routers and the
`independent routing of the packets in the IP network, law enforcement agencies are not
`able to monitor real-time IP applications such as Voice-over-IP (VoIP) calls.
`
`It would be advantageous to have a method of monitoring calls in an illtemet
`Protocol (IP)-based network. The present invention provides such a method.
`
`10
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`15
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`20
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`SUMMARY OF THE INVENTION
`In one aspect, the present invention is a method of monitoring a call from a
`
`mobile terminal (MT) in an IP-based network having a Gatekeeper that controls the
`
`network, a plurality of access routers that provide access to the network, and a
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`5
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`Monitoring Station having monitoring facilities and a database of MTs to be
`
`monitored. The method includes the steps of sending an access request from the MT
`
`to the Gatekeeper, sending a query from the Gatekeeper to the Monitoring Station
`
`asking whether the MT is to be monitored, and sending a reply from the Monitoring
`
`Station to the Gatekeeper indicating that the MT is to be monitored and providing an
`
`10
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`IP address where monitored packets are to be sent. This is followed by sending a
`
`monitoring request from the Gatekeeper to the access router associated with the
`
`monitored MT, the request identifying the MT to be monitored, instructing the access
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`router to monitor the MT, and providing the IP address where monitored packets are
`
`to be sent. When the access router detects a packet associated with the MT, the router
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`15
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`sends all packets associated with the MT to the Monitoring Station.
`
`When the monitored MT is handed off from a first base station to a second
`
`base station, and each of the base stations is controlled by a single Radio Network
`
`Controller (RNC), the RNC sends a monitoring request to the second base station.
`
`The monitoring request identifies the MT to be monitored, instructs the second base
`
`20
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`station to monitor the MT, and provides a unique call identification (Call ID) and the
`
`IP address where monitored packets are to be sent. The unique Call ID is assigned by
`
`the Gatekeeper. The RNC also sends a notification to the Gatekeeper that the MT is
`
`being served by the second base station, and includes the unique Call ID and a new
`
`transport address for the MT, if any.
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`25
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`When the monitored MT is handed off from a first base station controlled by
`
`a first RNC to a second base station controlled by a second RNC, and both RNCs are
`
`in a single Gatekeeper domain, the method performs the steps of sending identifying
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`information regarding the MT being monitored from the first RNC to the second RNC,
`
`and sending a monitoring request from the second RNC to the second base station, the
`
`30
`
`request identifying the MT to be monitored, instructing the second base station to
`
`monitor the MT, and providing the unique Call ID and the IP address where monitored
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`packets are to be sent. The second RNC also sends a notification to the Gatekeeper
`
`that the MT is being served by the second base station, and includes the Call ID and
`
`the new transport address for the MT. Whenever there is a change to the transport
`
`address of the MT, the Gatekeeper forwards the Call ID and the new transport address
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`5
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`to the Monitoring Station.
`
`When the monitored MT is handed off from a first base station controlled by
`
`a first RNC in a first Gatekeeper domain, to a second base station controlled by a
`
`second RNC in a second Gatekeeper domain, the method performs the steps of sending
`
`a notification from the first RNC to the second RNC that the MT is being monitored,
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`10
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`and sending a monitoring request from the second RNC to the second base station.
`
`The monitoring request identifies the MT to be monitored, instructs the base station
`
`to monitor the MT, and provides the unique Call ID and the IP address of a Monitoring
`
`Station where monitored packets are to be sent. The second base station then begins
`
`sending media packets having the MT address as a source address or destination
`
`15
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`address to the Monitoring Station. Then, the second RNC sends the unique Call ID
`
`it received and a new transport address for the MT to the second Gatekeeper. The
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`second Gatekeeper forwards this information to the Monitoring Station. This is
`
`followed by sending an access request from the MT to the second Gatekeeper, and
`
`allocating bandwidth to the MT by the Gatekeeper.
`In another aspect, the present invention is a method performed within a
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`20
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`Gatekeeper in an IP-based network. The method monitors a call from an MT and
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`routes the monitored call to a Monitoring Station having monitoring facilities and a
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`database ofMTs to be monitored. The method includes the steps ofreceiving in the
`
`Gatekeeper, a network access request from the MT, sending a query from the
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`25
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`Gatekeeper to the Monitoring Station asking whether the MT is to be monitored, and
`
`receiving in the Gatekeeper, a reply from the Monitoring Station indicating that the
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`MT is to be monitored and providing an IP address where monitored packets are to be
`
`sent. This is followed by sending a monitoring request from the Gatekeeper to the
`
`access router that is associated with the monitored MT and is providing access to the
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`30
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`network. The request identifies the MT to be monitored, instructs the access router
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`to send any packets associated with the MT to the Monitoring Station, and provides
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`the unique Call ID and the IP address where monitored packets are to be sent.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
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`5
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`The invention will be better understood and its numerous objects and
`
`advantages will become more apparent to those skilled in the art by reference to the
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`following drawings, in conjunction with the accompanying specification, in which:
`
`FIG. 1 is an illustrative drawing of an IP network modified in accordance with
`
`the teachings of the present invention to monitor a call between two IP terminals;
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`10
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`FIG. 2 is a message flow diagram illustrating the flow of messages when
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`setting up a call for monitoring in the IP network of FIG. 1 in accordance with the
`
`teachings of the present invention;
`
`FIG. 3 is an illustrative drawing of an IP network modified in accordance with
`
`the teachings of the present invention to monitor a call between an IP terminal and a
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`15
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`terminal in the Public Switched Telephone Network (PSTN);
`
`FIG. 4 is a message flow diagram illustrating the flow of messages when a
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`monitored mobile terminal is handed off from an old base station to a new base station
`
`controlled by the same Radio Network Controller (RNC) as the old base station;
`
`FIG. 5 is a message flow diagram illustrating the flow of messages when a
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`20
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`monitored mobile terminal roams into a new subnet within the same domain, and
`
`acquires a new RNC, a new base station, and a new transport address; and
`
`FIG. 6 is a message flow diagram illustrating the flow of messages when the
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`mobile terminal roams into a new domain and acquires a new Gatekeeper, a new RNC,
`
`a new base station, and a new transport address.
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`25
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`DETAILED DESCRIPTION OF EMBODIMENTS
`
`The present invention is described herein primarily m terms of the
`
`h1temational Telecommunications Union (ITU) H.323 protocol, but is equally
`
`applicable to both H.323 and the Session h1itiation Protocol (SIP) developed by the
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`30
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`h1temet Engineering Task Force (IETF). h1 particular, the term "Gatekeeper" which
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`is used herein refers to both an H.323 Gatekeeper and a SIP proxy server and registry.
`
`In addition, reference to an H.245 address herein also refers to a SIP address.
`
`In a typical IP network, PC clients or IP telephony terminals (fixed or mobile)
`
`are identified and addressed by an e-mail address (proxy/alias), or an IP address, or
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`5
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`both. Prior to making any calls, such terminals register with a Gatekeeper in an H.323
`
`network, or with a SIP proxy server in a SIP network. If the registration is accepted
`
`by the Gatekeeper, the Gatekeeper handles incoming calls to the terminal as well as
`
`outgoing calls from the terminal. The Gatekeeper maintains a subscriber profile that
`
`includes, among other things, the services to which the subscriber is entitled. For
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`10
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`simplicity, the term "mobile tenninal (MT)" is used herein to refer generically to IP
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`clients, both fixed and mobile since the most challenging monitoring tasks involve
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`intra-domain and inter-domain handoff of MTs.
`
`FIG. 1 is an illustrative drawing of an IP network 10 modified in accordance
`
`with the teachings of the present invention to monitor a call between two IP terminals.
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`15
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`IP Terminal-I 11, which may be originating a call, is connected to the IP network
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`through Access Router-I 12. Media traffic (i.e., data) 13 is carried by independent
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`paths through the network to Access Router-2 14 through which IP Terminal-2 15 has
`
`accessed the network. IP Terminal-2 may be the terminating ( destination) terminal.
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`Control signaling between the two subscribers is carried in a control plane 16 which
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`20
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`passes through a Gatekeeper 17, and from the Gatekeeper to a Monitoring Station 18
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`which may be operated by a law enforcement agency.
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`In order for the two IP subscribers 11 and 15 to communicate over the IP-based
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`network 10, they have to go through the Gatekeeper 17 which can be likened to a
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`mobile switching center (MSC) in a circuit-switched network. The Gatekeeper is the
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`25
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`brain of the network regarding the routing of calls. The Gatekeeper manages the
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`bandwidth ( with the help of other network entities), generates the accounting data, etc.
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`In a first scenario, the calling and called subscribers are within the same
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`domain. In that case, when a subscriber wants to make or receive a call, an Admission
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`Request (ARQ) message (when using H.323) is sent to the Gatekeeper. In response
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`30
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`to the ARQ message, the Gatekeeper allocates the bandwidth for the call or, if none
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`is available, the Gatekeeper denies the call. The present invention extends the
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`procedure performed by the Gatekeeper when a bandwidth allocation request (i.e.,
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`ARQ) is received from a device that is originating or receiving a call. Additionally,
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`new mandatory parameters are introduced in the ARQ message.
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`The Gatekeeper does not know which subscribers need to be monitored. Only
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`5
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`the law enforcement Monitoring Station has this information. The Monitoring Station
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`includes a database of all subscribers who should be monitored for security reasons.
`
`So for each call that is originated by or tenninated to a subscriber in its domain, the
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`Gatekeeper queries the Monitoring Station to determine whether the subscriber should
`
`be monitored.
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`10
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`FIG. 2 is a message flow diagram illustrating the flow of messages when
`
`setting up a call for monitoring in the IP network of FIG. 1 in accordance with the
`
`teachings of the present invention. In the illustrated example, IP Terminal-I 11 is the
`
`subscriber to be monitored. After Terminal-I sends an ARQ message 21 to the
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`Gatekeeper 17, the Gatekeeper performs the bandwidth allocation function at 22, and
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`15
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`then sends a monitor query message 23 to the Monitoring Station 18. The monitor
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`query message includes the H.245 source address and the H.245 destination address
`
`for the call, if available, as well as subscriber addressing information ( e-mail/proxy)
`
`and the unique Call ID that it generates for the call. The Monitoring Station checks
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`the database at 24 and returns a monitor reply message 25 to the Gatekeeper indicating
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`20
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`whether any of the parties in the call should be monitored, as well as the IP address of
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`the Monitoring Station to which the monitored conversation should be sent. In the
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`illustrated example, the message indicates that Terminal-I is to be monitored. If none
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`of the terminals is being monitored, the Gatekeeper then returns an Admission
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`Confirm (ACF) message 26 to Terminal-I. If any of the subscribers is being
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`25
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`monitored, the Gatekeeper sets a flag in the subscriber record at 27 indicating that fact.
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`The Gatekeeper finds, through normal IP routing protocols, the path for the
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`media to follow. The Gatekeeper obtains this information in the course of allocating
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`bandwidth since the policy related to the QoS of the call must be downloaded to all of
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`the routers in the media path. The routers, in this case, act as policy enforcement
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`30
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`points to ensure that the subscribers are respecting the QoS agreements. However, for
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`the sake of monitoring, it suffices that the Gatekeeper identifies only the access router
`
`associated with IP Terminal-I.
`
`Hence, the Gatekeeper is able to identify the access router for this call. The
`
`Gatekeeper then sends a Monitoring Request message 28 to the access router
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`5
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`associated with the subscriber (for example, Access Router-I), and includes the
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`Monitoring Station IP address and the unique Call ID for that call. Access Router-I
`
`sends back an Acknowledgment message 29. Once the Gatekeeper receives the
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`Acknowledgment message from the Access Router, the Gatekeeper sends an ACF
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`message 31 to Terminal-I.
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`10
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`It should also be noted that in IP networks, addressing is different in each
`
`media direction. Therefore, the IP address to be monitored is the source address in the
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`IP header while the monitored subscriber is initiating the conversation, and is the
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`destination field in the IP header while the monitored subscriber is listening. Thus,
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`while the Access Router performs its normal routing functions, it has to monitor both
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`15
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`the source and the destination addresses in the IP headers that it handles in order to
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`identify addresses that match the monitored address. Media packets then begin to flow
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`from the IP Terminal to Access Router-I at 32, and Access Router-I sends the packets
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`to the Monitoring Station at 33.
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`To send media packets to the Monitoring Station, the Access Router
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`20
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`encapsulates every identified packet with a new header that includes the router's
`
`address as the source address, and the Monitoring Station's address as the destination
`
`address. The unique Call ID is also included in the IP header. This enables the
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`Monitoring Station to correlate packets belonging to the same conversation. Other
`
`parameters may be included in the header as well. Upon receipt, the Monitoring
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`25
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`Station strips away the header and recovers the original packets. When the call is
`
`cleared, the com1ection from the access router to the Monitoring Station is also
`
`cleared.
`
`In another scenario, the calling and called subscribers are in different domains.
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`In that case, two different Gatekeepers must deal with the calling and called
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`30
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`subscribers. Additional information must be exchanged between the Gatekeepers as
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`part of the call setup for the management and coordination of monitoring a call.
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`Otherwise, both Gatekeepers may end up monitoring the same call.
`
`In this scenario, the originating Gatekeeper will likely not know the IP address
`
`of the destination. Thus, the originating Gatekeeper follows the same procedure
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`5
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`previously described. However, the query that the originating Gatekeeper sends to the
`
`Monitoring Station includes only the calling subscriber identity. If the calling
`
`subscriber is not the one being monitored, then the originating Gatekeeper returns an
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`ACF message and proceeds with normal call setup. During the setup, the originating
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`Gatekeeper forwards to the Gatekeeper that deals with the destination terminal, a
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`10
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`special flag infom1ing the destination Gatekeeper that the calling subscriber is not the
`
`one being monitored. The destination Gatekeeper follows the previously described
`
`procedure, including the monitoring procedure, when the called terminal sends an
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`ARQ message to accept the incoming call.
`
`On the other hand, if the calling subscriber is the one being monitored, the
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`15
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`originating Gatekeeper follows the same procedure described previously when it
`
`receives an ARQ message from the calling subscriber. The originating Gatekeeper
`
`then sends a flag to the destination Gatekeeper identifying the calling subscriber as a
`
`subscriber to be monitored. The destination Gatekeeper follows the same procedure
`
`previously described when the called terminal sends an ARQ message to accept the
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`20
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`call, but bypasses the monitoring procedure.
`
`It should also be noted that in this scenario, the originating Gatekeeper receives
`
`only the destination IP address as part of the call setup procedure. Therefore, the
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`originating Gatekeeper must send a second Monitoring Request Message to the Access
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`Router to convey the destination IP address.
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`25
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`FIG. 3 is an illustrative drawing of an IP network 20 modified in accordance
`
`with the teachings of the present invention to monitor a call between an IP terminal (IP
`
`Terminal-3)41 and a terminal in acircuit-switchednetwork(PSTNTerminal) 42 such
`
`as the Public Switched Telephone Network (PSTN) 43. If the subscriber to be
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`monitored is in a circuit-switched network such as the PSTN, the call goes through a
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`3 0
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`Gateway 44 to the IP subscriber in the IP network. If the subscriber to be monitored
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`is on the PSTN side, then existing procedures in the PSTN ensure that monitoring
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`takes place. However, if the subscriber to be monitored is on the IP side, the procedure
`
`described previously is invoked when the called subscriber (to be monitored) sends an
`
`ARQ message to the Gatekeeper to accept an incoming call.
`
`Again in this case, coordination is needed to ensure that no double monitoring
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`5
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`occurs when both subscribers are to be monitored. Therefore, for an H.323 endpoint
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`of the gateway type (as opposed to a terminal type of endpoint), the ARQ message sent
`
`to the Gatekeeper from the Gateway 44 includes a flag to indicate whether an
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`incoming call is already being monitored from the PSTN side. The Gatekeeper then
`
`bypasses the monitoring procedure. The PSTN, of course, must convey this
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`10
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`information to the Gateway so that it can be passed to the Gatekeeper.
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`In one
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`embodiment, Integrated Services User Part (ISUP) signaling is extended to carry this
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`information. Optionally, specialized control messages can convey the information to
`
`the Gateway from the entity that is coordinating the monitoring in the PSTN. In all
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`cases, the globally unique Call ID must be transferred to uniquely identify the
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`15
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`impacted call.
`
`Mobility/Handoff Scenarios
`
`Mobility adds another level of complexity to the task of IP monitoring due to
`
`the potential changing of the point of attachment of the MT to the network. In this
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`case, the base stations serve as Access Routers since they are the closest point of
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`20
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`attachment to the subscriber. However, Gatekeepers do not communicate directly with
`
`base stations since base stations belong to the Radio Access Network (RAN).
`
`Therefore, the Gatekeepers must go through the Radio Network Controller/Base
`
`Station Controller (RNC/BSC) that controls these base stations for all requests to the
`
`base stations regarding the monitoring of subscribers.
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`25
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`Therefore, the same procedures described above for monitoring fixed
`
`subscribers still apply for mobile subscribers except that all Gatekeeper requests that
`
`are sent directly to the Access Routers for fixed subscribers, are sent instead to the
`
`RNC. The RNC, in tum, sends them to the base stations.
`
`FIG. 4 is a message flow diagram illustrating the flow of messages when the
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`30
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`monitored mobile tenninal (MT) is handed off from an old base station (BS-1) 51 to
`
`a new base station (BS-2) 52 controlled by the same RNC 53 as the old base station.
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`Case 6:20-cv-00272-ADA Document 65-19 Filed 03/14/22 Page 12 of 25
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`WO 01/89145
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`PCT/SE0l/00972
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`When the MT does not change its transport address, but roams in a new base station,
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`the link layer in the base station ensures delivery of the call to the MT. After handoff
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`occurs at 54, the RNC instructs BS-2 to monitor the subscriber at 55 and includes the
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`address of the Monitoring Station and the unique Call ID. The RNC then informs the
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`Gatekeeper 17 of the new base station at 56, and includes the unique Call ID to
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`identify the impacted call. If there is a change in the transport address of the mobile
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`terminal as a result of the handoff, the new address is also sent to the Gatekeeper by
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`the RNC. The RNC learns the new address during the handoff procedure. In the
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`preferred embodiment, this information is passed only for monitored subscribers in
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`order to minimize the signaling load. At 57, the Gatekeeper forwards the Call ID and
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`the new transport address, if any, to the Monitoring Station 18. At 58, media is passed
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`from BS-2 to the Monitoring Station.
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`FIG. 5 is a message flow diagram illustrating the flow of messages when the
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`monitored MT is handed off from an old base station (BS-1) 61 controlled by an old
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`RNC (RNC-1) 62 to a new base station (BS-3) 63 controlled by a new RNC (RNC-2)
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`64 within the same Gatekeeper domain. Thus, in this scenario, the MT roams into a
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`new subnet within the same domain, and acquires a new RNC, a new base station, and
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`a new transport address. At 65, the MT is handed off from BS-1 to BS-3. At 66,
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`RNC-lforwards to RNC-2 all of the pertinent information regarding the subscriber
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`being monitored, including the unique Call ID for the call being monitored. At 67, the
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`new RNC (RNC-2) instructs the new base station (BS-3) to monitor the subscriber,
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`and includes the unique Call ID and the address of the Monitoring Station.
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`Since the mobile terminal changed transport addresses, it is required to register
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`its new transport address with the Gatekeeper 17. Therefore, at 68, RNC-2 informs
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`the Gatekeeper of the new base station and the new transport address assigned to the
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`mobile terminal. The unique Call ID is also included. At 69, the new transport
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`address and the Call ID are passed by the Gatekeeper to the Monitoring Station 18 so
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`that all the packets belonging to the same monitored call can be correlated. Thereafter,
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`media packets are forwarded from BS-3 to the Monitoring Station at 70.
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`FIG. 6 is a message flow diagram illustrating the flow of messages when the
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`mobile tenninal roams into a new domain and acquires a new Gatekeeper, a new RNC,
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`Case 6:20-cv-00272-ADA Document 65-19 Filed 03/14/22 Page 13 of 25
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`WO 01/89145
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`PCT/SE0l/00972
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`a new base station, and a new transport address. The monitored MT 71 is initially
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`operating in IP Network-I which includes Gatekeeper-I 72. RNC-1 73 and BS-1 74
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`are in RAN-1 which provides radio access for IP Network-I. At handoff 75, the
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`monitored MT is handed off from BS-I to a new base station (BS-2) 76 controlled by
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`a new RNC (RNC-2) 77. RNC-2 and BS-2 are in RAN-2 which provides radio access
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`for IP Network-2 which includes Gatekeeper-2 78. Monitoring Station 18 is
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`monitoring the call with the MT.
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`At 79, the new RNC (RNC-2) is infonned by RNC-1 that the MT is being
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`monitored. At 81, the RNC-2 instructs the new base station (BS-2) to monitor the
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`subscriber, and includes the unique Call ID and the address of the Monitoring Station.
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`Media then begins to flow from BS-2 to the Monitoring Station at 82. RNC-2 then
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`informs Gatekeeper-2 at 83 that a new subscriber is now roaming in its service area,
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`and that the new subscriber needs to be monitored. RNC-2 includes the IMSI for the
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`MT, the unique Call ID, and the MT's new transport address in the message to
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`Gatekeeper-2. Every time there is a change in the transport address of a monitored
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`mobile terminal, the controlling Gatekeeper must infonn the Monitoring Station of the
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`new transport address. Thus, at 84, the new transport address and the Call ID are
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`passed to the Monitoring Station. The unique Call ID is used by the Monitoring
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`Station to track all packets belonging to the same conversation. In addition, the Call
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`ID is used by any Gatekeeper that handles a portion of the call ( other than the original
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`Gatekeeper) to report the same call to the Monitoring Station. Thus, during a handoff
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`scenario, the RNC passes the Call ID to the same Gatekeeper ifthere is no change of
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`domain, and to the new Gatekeeper when there is a change of domain.
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`At 85, Gatekeeper-2 sets a flag in the subscriber record for MT 71 indicating
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`that the MT is in its area and is being monitored. The flag also indicates that a
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`subscriber will soon have to register with his transport address. Since the MT changed
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`its transport address, the MT is required to register with the new Gatekeeper and report
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`its new transport address. A registration timer is started when the flag is set in case the
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`registration never arrives (registration is lost, subscriber hangs up, etc.).
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`At 86, an ARQ message is sent from the MT to Gatekeeper-2. When the ARQ
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`arrives, the registration timer in Gatekeeper-2 is stopped at 87, and bandwidth is
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`Case 6:20-cv-00272-ADA Document 65-19 Filed 03/14/22 Page 14 of 25
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`WO 01/89145
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`PCT/SE0l/00972
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`allocated. Gatekeeper-2 then returns an ACF message 88 to the MT. Gatekeeper-2
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`knows that the MT is being monitored because Gatekeeper-2 was infonned by RNC-2.
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`Therefore, Gatekeeper-2 does not perform the monitoring procedure associated with
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`the new registration. Thus, double monitoring of the conversation is avoided.
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`Whenever any monitored subscriber hangs up, a De-Admission Request is sent
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`to the Gatekeeper. The Gatekeeper clears the flag for monitoring the subscriber and
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`sends a message to the.Monitoring Station to stop the monitoring of the call. This
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`message is also propagated to the Access Router performing the monitoring.
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`It is thus believed that the operation and construction of the present invention
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`will be apparent from the foregoing description. While the method shown and
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`described has been characterized as being preferred, it will be readily apparent that
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`various changes and modifications could be made therein without departing from the
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`scope of the invention as defined in the following claims.
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`Case 6:20-cv-00272-ADA Document 65-19 Filed 03/14/22 Page 15 of 25
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`WO 01/89145
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`PCT/SE0l/00972
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`WHAT IS CLAIMED IS:
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`1.
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