Patent Publication Number: US-2002009973-A1

Title: Communication network and method for providing surveillance services

Description:
CROSS REFERENCE TO RELATED APPLICATION  
     [0001] This application is based on prior U.S. patent application No. 60/195,723, filed Apr. 7, 2000, and priority thereto is hereby claimed. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates generally to communication networks, and more particularly, to a communication network, an apparatus and a method for providing surveillance services.  
       BACKGROUND OF THE INVENTION  
       [0003] Under certain circumstances, and with appropriate authorization, law enforcement agencies (LEA) are permitted to legally intercept and monitor communications between individuals that may be targets of an investigation. A common technique, known as wiretapping, involves intercepting telephonic communications between individuals by “tapping” into the communication.  
       [0004] Plain old telephone systems (POTS) and early wireless communication systems incorporating, Class 4 or Class 5 exchanges, a Mobile Switching Center (MSC) and the like, employ circuit switching techniques to connect a calling party to a called party via a communication network. The call is completed upon successfully establishing the circuit between the parties, and the circuit becomes a dedicated link between the parties for carrying on the telephonic communications. All voice communication between the parties is then carried on this circuit.  
       [0005] To provide surveillance, or wiretapping, in such circuit switched systems required only determining and “tapping” the circuit at an appropriate location along the circuit. A circuit is dedicated to the call, and because all of the communications are carried on this circuit, the LEA can be assured of intercepting the entire communication, including in-band and out-of-band call signaling, between the individuals under surveillance from this one tap.  
       [0006] Evolution of communications technology will render obsolete the circuit switched network for both voice and data communication networks. In fact, circuit switched networks are being replaced by packet-based communication networks. In packet-based networks, the information carried by the network, for example data or encoded voice, is organized into packets, and the network carries these packets from the sending party to the receiving party. Within the network there is no single path or “circuit” that carries the packets from the sending party to the receiving party. Instead, the network may be considered a fabric of links, switches and routers that carry packets in an efficient manner. Packets associated with the communications of a first party with a second party may travel on any number of paths. This arrangement of the packet based communication network permits more efficient utilization of communication resources, and hence, permits the communication network to carry more information, with greater stability. Thus, the packet based communication network can service a greater number of users communicating greater amounts of information, i.e., both voice and data.  
       [0007] The Communications Assistance for Law Enforcement Act of 1994 (CALEA) requires that all US based wireline, cellular and broadband personal communication services (PCS) carriers provide the capability of legal, undetectable, bearer and call signaling intercept to law enforcement agencies for any subscriber utilizing their network. CALEA implementation, which is governed by Federal Communication Commission (FCC) regulations, must be completed by Jun. 30, 2000 for non-packet-based networks and by Sep. 30, 2001 for packet-based networks. While the FCC has specified the required functionality, it has not specified or recommended architecture for achieving compliance with its regulations.  
       [0008] As described above in connection with circuit-based, or non-packet-based networks, providing surveillance capability generally requires only determining the particular circuit established for a communication, and intercepting both the bearer and call signaling information carried on that circuit. However, in packet-based networks no single circuit or path carries the data packets which include the bearer and call signaling information. To ensure complete surveillance, it is necessary to ensure that all packets associated with a communication are identified regardless of the path assigned to any particular packet.  
       [0009] Additionally, the FCC regulations specify certain functional requirements beyond bearer and call signaling intercept that must be met for compliance with the CALEA legislation. The regulations are completely set forth in the interim standard J-STD-025, available from the Federal Communication Commission, 445 12 th  Street S.W., Washington, D.C., 20554. Among these requirements are a capability to provide: content of subject-initiated conference calls, party hold, join, drop on conference call, in-band and out-of-band signaling, timing information, dialed digit extraction, and no interruption of call performance, billing, etc. as a result of CALEA implementation.  
       [0010] Thus, there is a need for a communication network and method that includes surveillance capability and which utilizes packet switched data techniques for providing communication services. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a block diagram illustration of a communication network in accordance with a preferred embodiment of the present invention.  
     [0012]FIG. 2 is a call flow diagram illustrating a method of surveillance in a packet data network in accordance with a preferred embodiment of the present invention.  
     [0013]FIG. 3 is a block diagram illustration of a communication network in accordance with another preferred embodiment of the present invention.  
     [0014]FIG. 4 is a call flow diagram illustrating a method of surveillance in a packet data network such as illustrated in FIG. 3.  
     [0015]FIG. 5 is a block diagram illustration of a communication network in accordance with yet another preferred embodiment of the present invention.  
     [0016]FIG. 6 is a block diagram illustration of a communication network in accordance with still another preferred embodiment of the present invention.  
     [0017] FIGS.  7 - 10  are call flow diagrams illustrating a method of providing surveillance in a packet data network such as illustrated in FIG. 6.  
     [0018]FIG. 11 is a block diagram illustration of a communication network in accordance with yet another preferred embodiment of the invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0019] In accordance with the preferred embodiments of the invention, a communication network utilized for providing communications between a first party and a second party includes a surveillance server within a core network to provide communication surveillance capability. The core network may be a packet data network, and the surveillance server is operable responsive to trigger information to establish communications surveillance. Communication surveillance may be established by creating duplicate bearer packets of those data packets carrying the communicated data between the parties, creating duplicate control packets of those data packets carrying in-band or out-of-band call control information between the parties and within the packet data network, and/or various combinations thereof. The duplicate bearer packets and the duplicate control packets are routed to appropriate authorized law enforcement agencies for providing surveillance. Since these bearer packets are digitally encoded, the law enforcement agency will require encoding information on the bearer stream so that the packets can be decoded. Therefore, bearer packet encoding information must be sent to the law enforcement agency prior to initiating the duplication of bearer packets.  
     [0020] Consistent with the preferred embodiments of the present invention, the surveillance server (e.g., feature server) may be disposed within a packet data network and apart from external networks accessing the core network, the surveillance server may be associated with one or more network access servers and/or the surveillance server may be associated with one or more of the external accessing networks.  
     [0021] In accordance with preferred methods of providing surveillance within a packet data network, a surveillance server is provided either associated with or apart from the core network and in communication with the core network. The surveillance server identifies a trigger event, and responsive to the trigger event, causes the creation of duplicate bearer packets and/or duplicate control packets, and routes the duplicate packets to appropriate authorized law enforcement agencies.  
     [0022] With reference to FIG. 1, a communication core network is coupled for communication with a radio access network  12 , a public switch telephone network (PSTN)  14 , a packet data network and/or the Internet  16 , and a Signaling System  7  (SS 7 ) network  18 . It should be appreciated that the core network  10  may be coupled, via gateways (e.g., an SS 7  Gateway  28 , a packet gateway  30  or a PSTN gateway  32 ), for communication to additional networks of operating under virtually any protocol.  
     [0023] Within the core network  10  are a number of elements including a services client  20 , a PSTN/MGC  22 , a relay client  24 , and a CALEA feature server  26 . The relay client  24  provides an interface between the core network  10  and the radio access network  12  for providing wireless communication services to subscribers, not shown, utilizing the radio access network  12  for wireless voice and data communications. Within the radio access network  12 , a bearer client  13  provides the communication services to the subscribers, and is interfaced, such as by interface  15 , to the relay client  14 . Interface  15  is an ATM or IP signaling interface that relays radio access network signaling, possibly H.323, SIP, IS-634, or others, to the Services Client  20 . Additionally, a SS 7  gateway  28  couples the core network  10  to the SS 7  network  18 , a packet gateway  30  couples the core network  10  to the Internet  16  and a PSTN gateway  32  couples the core network  10  to the PSTN  14 . The convention used in FIG. 1 and throughout the drawings is that arrowed lines denote signaling information while non-arrowed lines denote bearer information.  
     [0024] The CALEA feature server  26  provides the CALEA feature application within the core network  10 . The CALEA feature server  26  interfaces to the services client  20  via a hypertext transfer protocol (HTTP) or other text based applications programming interface (HTTP/text API)  34 . The CALEA feature server  26  further interfaces with the relay client  24  via a feature application programming interface (FAPI)  36  to control duplication of bearer streams and processing of in-band signaling in the duplicated bearer streams. Additionally, the CALEA feature server  26  interfaces with the law enforcement agency (LEA)  25  via GENMAP link  27 , for providing out-of-band call signaling information such as dialed digits, call-waiting invocation, call feature invocation, conferencing adds/drops/etc. GENMAP, as is known in the art, generally refers to an ANSI-41, GSM MAP or similar signaling protocol.  
     [0025] The services client  20  provides the call processing engine within the core network  10  for providing communication services to users of the core network  10 . The services client  20  maintains the call model and state for subscribers in the radio access network  12 .  
     [0026] In accordance with the preferred embodiments of the invention and upon invocation of CALEA services for a targeted subscriber(s), the services client  20  provides point-in-call (PIC) call signaling information to the CALEA feature server via the interface  34 . This interface is a text based API such as HTTP or a more advanced API for feature processing. Additionally, the services client  20  interfaces with the relay client using a Relay Client Control Protocol (RCCP) connection  29  (based on H.248 signaling or MGCP) to manage the original bearer streams  31  pertaining to a subscriber&#39;s service requests.  
     [0027] The relay client  24  provides management of bearer streams  31 , i.e., encoded voice or data, for active calls and/or conferences in the core network  10 . In accordance with the preferred embodiments of the invention, the relay client  24  provides a capability to generate duplicate bearer streams  38  for communication to a LEA upon request from the CALEA feature server  26 . Such duplicate bearer streams may be a single combined stream (full-duplex for a two party call and possibly all members of a conference call), or the relay client  24  may duplicate and provide all or a sub-set of all of the bearer streams  31  to the LEA  25 , as requested by the LEA  25 . Additionally, and in accordance with the preferred embodiments of the invention, the relay client  24  may also provide call signaling information in-band with the duplicate bearer stream  38 , may exclude such call signaling information from the duplicate bearer stream or may provide the call signaling information as a separate data stream.  
     [0028] In accordance with the preferred embodiment of the invention shown in FIG. 1, the CALEA function resides within the CALEA feature server  26 , which provides surveillance services within the core network  10  as a subscribed service. The service is authorized and activated under the guidance of the requesting LEA. The CALEA feature server  26  controls the relay client  24  via the xGCP link  36  (XGCP refers to the family of protocols SGCP, MGCP, and in the future MEGACO/H.248) to cause the relay client  24  to provide the duplicate bearer streams  38  to the LEA  25  via the packet gateway  30  and the packet data network  16  in a manner that is unobtrusive to the original streams. The CALEA feature server  26  also controls the relay client  24  via the xGCP link  36  to provide any required in-band signaling for the duplicate bearer streams  38 . The CALEA feature server  26  is triggered from the services client  20  via link  34  at required PICs to provide the required out-of-band signaling information to the LEA  25  over the GENMAP link  27 .  
     [0029] A basic surveillance services flow that may be applied with the preferred embodiment of the invention shown in FIG. 1 may start with CALEA service logic being downloaded to the services client  20  when a “targeted” subscriber registers with the core network  10 . This logic download provides the services client  20  with access to the CALEA feature server  26  for the targeted subscriber.  
     [0030] The CALEA service logic may include the necessary triggers, and will include at least one trigger, and provides the LEA  25  with required call signaling information (dialed digits, service invocation, etc.) and proper instructions for generating the duplicate bearer streams  38 . Upon detection of the at least one trigger associated with the targeted subscriber, such as registration, call origination, call termination, service invocation (e.g., call waiting, conference call, call forwarding, message retrieval, etc.) the services client  20  call model implements the surveillance service logic, which, in turn, interfaces with the CALEA feature server  26 . The CALEA feature server  26 , in turn, interfaces with the relay client  24  to provide the duplicate bearer streams  38  (e.g., merged, individual or sub-set bearer streams) to the LEA  25  using RTP over a secure Internet connection (such as defined in IPSec of the Internet Engineering Task Force) through the packet gateway  30 . The CALEA feature server  26  forwards the requested signaling streams to the LEA  25  using the GENMAP link  27  over the IPSec through the packet gateway  30 . Importantly, the original call signaling and bearer streams  31  are unaffected. The relay client  24  becomes the anchor point for targeted subscribers engaged in active calls. Also, core path optimization is deactivated if the call hands-off to another core network.  
     [0031] A representative call flow  200  for the system shown in FIG. 1, is illustrated in FIG. 2, wherein like reference numerals are used to represent like processes. FIG. 2 represents a surveillance service wherein the bearer streams are duplicated for forwarding to the LEA  25 . Not shown, is an initial request by the LEA  25 , via the packet gateway  30  for surveillance services in connection with a particular subscriber. This request contains the surveillance type information, which may be retained within the CALEA feature server  26 , or as described in connection with alternate preferred embodiments of the invention, in other suitable locations within the core network  10 .  
     [0032] As shown in FIG. 2, the targeted subscriber originates a call and the call is about to be connected. The services client  20  forwards a call connect trigger  202  to the CALEA feature server  26 . The call connect trigger  202  includes information necessary for implementing the requested surveillance service, and may include the RTP stream endpoint(s), vocoder type, requesting LEA identification, requesting LEA address, and the like. The CALEA feature server  26  forwards a duplicate bearer stream signal  204  using the xGCP link  26  to the relay client  24 , and the relay client  24  forwards the LEA address information  206  to the packet gateway  30 .  
     [0033] The packet gateway  30  makes an IPSec negotiation request  208  to the requesting LEA  25  via an unsecured link  41 . The security association is negotiated according to IPSec rules, and the LEA  25  provides an IPSec negotiation response  210 . The packet gateway  30  sends an acknowledgement  212  of the IPSec negotiation to the relay client  24 , and the relay client  24  begins sending the duplicate bearer streams  38 , using RTP. The duplicate bearer streams are then communicated from the packet gateway to the LEA  25  using the negotiated secure connection.  
     [0034] One of ordinary skill in the art will appreciate the modifications necessary to the above-described call flow  200  for triggering surveillance services responsive to call termination, services invocation, and other similar events occurring within the communication network  700 .  
     [0035]FIG. 3 shows a communication network  300  in accordance with an alternate preferred embodiment of the invention. The communication network  300  includes a packet-based core network  310 , and takes advantage of the distributed nature of the core network  310  for providing surveillance services. In accordance with the preferred embodiments of the invention, the communication network  300  makes use of several functional elements that are typical of and therefore expected to be resident within the core network  310  for providing communication services. Advantageously, the architecture of communication network  300  minimizes additional development that would otherwise be required to provide functions necessary to support surveillance services within the communication network  300 .  
     [0036] The core network  310  includes a packet data gateway  312  for linking to a packet data network  314 , an SS 7  gateway  316  for linking to a PSTN  318 , a circuit gateway  320 , additional feature servers  322 , a conference feature server  324 , a H.323/A+Client Gatekeeper  326 , and an access server  328 . Subscribers (not shown) access the core network  310  via an access network  330 , such as a radio access network, and the access server  328 . The core network  310  further includes a subscriber services database  332 , e.g., a home location register database as is well known in cellular communication systems. As shown in FIG. 3, additional feature servers  322  may include a billing server  336 , a location server  338  and a short message server  340 .  
     [0037] As shown in FIG. 3, core network  310  also includes a surveillance distribution server (SDS)  334 . As will be described in more detail below, the SDS  334  may provide the following functions: conversion of call set-up messages and call-related information to a standard message format, for example, to the J-STD-025 message standard, for communication to a requesting LEA; delivery of the standard messages to the LEA; initiation of requests to the core network elements to provide subscriber information, for example, location information; reception of packet data from other core network elements for communication to the LEA, and support a subscriber surveillance database.  
     [0038] To support the functionality of the SDS  334 , it may be necessary to interface the SDS  334  with the H.323/A+Client gatekeeper  326  and one or more of the feature servers  322 , such as location server  338 . The implementation shown in FIG. 3 does utilize and rely upon the conference feature server  324  being within or interfaced to the core network  310  to handle combining data from the surveillance subject and associate for delivery to the LEA. A conference feature server  324  will typically exist within the core network  310  for supporting POTS features, such as three-way calling, call forwarding, etc.; however, it will also be appreciated that the function of the conference feature server  324  may be provided within one of the additional feature servers  322 , another element of the core network  310  or may be extracted from the core network  310 .  
     [0039] It will also be appreciated that there may be several locations within the core network  310  within which subscriber surveillance data may be retained. However, adaptation of the home location register (HLR) to include a data structure for retaining the subscriber surveillance data advantageously reduces the amount of provisioning required for implementing surveillance services and provides an implementation cost savings. For purposes of the implementation shown in FIG. 3, it will be assumed that the HLR is utilized in this manner and accessed via the subscriber services management system  333  that is used for provisioning. The surveillance data that may be included in the subscriber services database  332  is wire tap type, start date and time, stop date and time, IP addresses for the requesting LEAs, case identifications, and LEA identification information.  
     [0040] In accordance with the embodiment of the invention shown in FIG. 3, responsive to invocation of surveillance services, the SDS  334  instructs the access server  328  to generate duplicate bearer data packets and to transmit the duplicate bearer data packets to the conference feature server  324 . The conference feature server  324  combines and sums the duplicate bearer data packets into a single path and communicates them to the circuit gateway  320  to transmit to the requesting LEA (not depicted). The circuit gateway communicates to the SDS  334  the circuit or circuits being used to transmit the bearer data to the LEA, and the SDS  334  also provides this information to the LEA.  
     [0041] The H.323 Client gatekeeper  326  detects when a call set-up message is being transmitted by a targeted subscriber within the access network  330 . The H.323 Client gatekeeper  326  transmits duplicate call set-up messages to the SDS  334 , and the SDS  334  translates these messages into standard messages for communication to the LEA. The H.323 Client gatekeeper  326  will also transmit messages to the SDS  334  from other elements of the core network  310 . For example, messages relating to the utilization of the feature servers  322  may be transmitted, or the subscriber services database  332  may transmit messages that the targeted subscriber has made changes to their feature profile. Additionally, the subscriber services database  332  will also inform the SDS  334  whenever the targeted subscriber has roamed into a different network.  
     [0042] By providing an interface to the billing server, the SDS  334  may obtain and retain billing records whenever surveillance services are provided to a LEA. Thus, the communication network operator may more accurately recoup the cost of providing surveillance services.  
     [0043] Surveillance services relating to short message data may be handled by either of the access server  328  or the H.323 Client gatekeeper  326  eliminating the need to interface the short message server  340  to the SDS  334 . Whether the access server  328  or the H.323 Client gatekeeper  326  controls the transmission of short message data and information may depend on whether the short message data and information is considered bearer data or signaling data.  
     [0044]FIG. 4 illustrates a typical call flow  400  wherein surveillance services are provided using a network configured as shown in FIG. 3. At step  402 , the targeted subscriber originates a communication, for example, by dialing digits and pressing send on a cellular radiotelephone. At step  404 , the H.323 Client gatekeeper  326  makes an inquiry of the subscriber services database  332 , and at step  406  the surveillance services data is obtained from the subscriber services database and communicated to the H.323 Client gatekeeper  326 . From the H.323 Client gatekeeper  326 , at step  408 , the surveillance services data is communicated to the access server  328 . Alternatively, the access server  328  may maintain a separate, local surveillance services database.  
     [0045] At step  410 , the H.323 Client gatekeeper  326  continues with the targeted subscriber&#39;s origination request, and transmits a copy of the origination data to the SDS  334 . The SDS  334  receives the origination data and translates the data to the standard data format and transmits the translated origination data to the requesting LEA through the packet gateway  312 , step  412 . Once the origination attempt is answered at the far end, and bearer data, either voice or data, is sent between the targeted subscriber and the access server  328 , at step  414 , the access server  328  duplicates the bearer data and sends it to the conference feature server  324 . The access server  328  must send duplicated bearer data for each LEA requesting surveillance services for the subject. That is, multiple LEAs may be requesting surveillance services on the same targeted subscriber, and therefore multiple duplicate copies of the bearer data will be generated, one each for each requesting LEA.  
     [0046] The conference feature server  324  assigns resources to combine and transmit the duplicated bearer data to each of the requesting LEAs, and the combined data is then sent to the circuit gateway for transmission to the LEAs, step  416 . At step  418 , the circuit gateway transmits the combined data to the LEAs, and at step  420  the circuit gateway transmits circuit identification data to the SDS  334  for reporting to the LEAs in standard messages, step  422 .  
     [0047] The SDS  334  may also request location data from the location server  338 . The location data is likewise placed into the standard message format by the SDS  334  and transmitted to the LEAs. Likewise, one of ordinary skill in the art will readily appreciate and understand the modifications necessary to the above-described call flow for providing surveillance services triggered from call termination, services invocation, and other similar events occurring within the communication network  300 .  
     [0048]FIG. 5 illustrates a communication network  500  similar in configuration to that shown in FIG. 1, and like elements are identified using a reference numeral beginning with the number “ 5 .” For example, core network  10 , in FIG. 1, is shown as core network  510  in FIG. 5. In FIG. 5, the CALEA feature server  526  is no longer resident within the core network  510 , but instead is disposed external to the core network  510 . In this arrangement it is necessary to interface the CALEA feature server  526  to the services client  520 , the relay client  524  and the packet gateway  530 . Additionally, as shown in FIG. 5, the CALEA feature server  526  communicates via a link  542  with an authentication authority  540 , for example, a designated governmental authority, which can authenticate requests for surveillance services.  
     [0049] In a preferred embodiment of the invention, and in connection with the communication network  500 , a LEA  525  requests surveillance services for a targeted subscriber over an IPSec secure connection via the packet gateway  530 . The services request is communicated through the core network  510  to the CALEA feature server  526 . The CALEA feature server  526  engages in a dialogue with the authentication authority  540 , and is provided all necessary information associated with the requested surveillance. The CALEA feature server  526  communicates with the appropriate network operator, for example, the operator of core network  510 , authorizing the surveillance request and placing the surveillance order.  
     [0050] The CALEA feature server  526  may then inject logic into the appropriate network elements within core network  510 , for example relay client  524 , services client  520  and/or other feature servers and gateways, to enable the requested surveillance services.  
     [0051] When the targeted subscriber initiates a service that triggers surveillance, for example, originating a call, the relay client  524  notifies the CALEA feature server  526 , and the network elements within the core network  510  provide the CALEA feature server  526  with the necessary surveillance data, for example, location. The relay client  524  also advises the assigned resource ID to be used for subscriber initiated service.  
     [0052] The CALEA feature server  526  instructs the relay client  524  to provide a duplicate bearer stream to the authorized LEA  525 , using the LEA&#39;s IP address information provided when the LEA  525  made the surveillance services request. Alternatively, the CALEA feature server  526  could request the multicast address currently being used for the target subscriber and instruct the packet gateway  530  to send multicast information to the LEA&#39;s IP address. The relay client  524  routes the duplicate bearer stream to the LEA via the packet gateway  530  (and/or a circuit gateway). Other feature servers within the core network  510  are also instructed to route call signaling, short message data, and the like to the LEA  525  via the packet gateway  530  and using the LEA&#39;s IP address.  
     [0053] As is appreciated from the embodiment of the invention describe in connection with FIG. 5, surveillance services may be provided as an extracted feature. Thus, surveillance services may be added without extensive reconfiguration of the architecture of the core network  510 . Providing authentication via the authentication authority  540  ensures that surveillance services are not implemented absent appropriate authorization. Moreover, in accordance with the embodiment of the invention shown in FIG. 5, surveillance services may be implemented using existing customer equipment.  
     [0054]FIG. 6 illustrates a communication system  600  in accordance with another preferred embodiment of the invention. As in the previously described embodiments of the invention, signaling information is indicated by arrowed lines while bearer traffic is indicated by solid lines. The system  600  includes a bearer distribution network  602  that is coupled to a packet data network  604  and to a PSTN  606 . The communication system  600  also includes a radio access network  608  and a core network  610 .  
     [0055] The bearer distribution network  602  functions to transport IP bearer traffic (e.g. voice or data) within the communication network  600 . For example, the bearer distribution network may include SDUs, MCUs, IP switches and signaling and media gateways. It should be appreciated that various combinations of these elements may be used depending on the type of source and destination parties/devices and the services provided. For example, in communication systems supporting mobile-to-mobile calling and/or packet data calling services, network resources may not be required.  
     [0056] The radio access network  608  is coupled to both the bearer distribution network  602  and to the core network  610  and provides wide-area wireless communication services in accordance with one or more communication standards. More particularly, within the core network  610 , the radio access network is coupled to a call control server  612 . The control server  612  is a functional entity within the core network  610  that incorporates the IP network call/session establishment and feature interaction. This is a distillation of such functions as radio network controller, services client, session manager, and the like. The call control server  612  is also coupled to a CALEA feature server  614  within the core network  610 .  
     [0057] A mobility server  616 , a location server  618 , a profile server(s)  620 , an operations server  622  and other feature servers  624  are provided within the core network  610  and are coupled to the CALEA feature server  614 . The mobility server  616  is the functional equivalent of the Visitor Location Register (VLR) of current cellular communication systems. The location server  618  manages the locations gathering and provides the best possible coordinate location of mobile subscribers operating in the radio access network  608 . The profile server  620  is a repository of mobile subscribers require for feature management and control. A home location register (HLR) is an example of a profile server  620 . The operations server  622  provides the functionality and operations necessary to provision the CALEA feature server  614  with information required for providing surveillance services. For example, the operations server  622  will provide the CALEA feature server  614  with the identity of the surveillance target as well as the identity of the LEA requesting the surveillance services.  
     [0058] The bearer distribution network is also coupled to a collection gateway  626 . The collection gateway  626  is a media gateway, which has an interface to law enforcement. It may also include functionality to encrypt/decrypt intercept signaling and bearer data, and may also contain multicast group client capability for intercepting multicast subject content. The collection gateway  626  interfaces to an intercept access point  628 , which is the collection point for surveillance content and data, and the point from which the LEAs access and acquire the surveillance content and data.  
     [0059] With reference still to FIG. 6, and reference also to FIGS.  7 - 10 , the operation of the communication system  600  for providing surveillance services is described.  
     [0060] Upon reception of appropriate authorization from a law enforcement agency, for example, a court order authorizing wiretapping, the operator provisions surveillance of the subject via the operations system. At step  702 , the operations server  622  sends the provisioning information to the CALEA Feature Server  614 . This includes the CASE ID which identifiers the law enforcement agency and the particular surveillance case. Also included is the subject&#39;s identity such as his or her directory number and name. If encryption of the signaling is desired, a key may be distributed to the network entities that will provide surveillance information.  
     [0061] Based on the subscriber and agency information, the CALEA feature server  614  instructs the multicast client function in the appropriate collection gateways  626  to listen for multicast announcements of the identified subject, step  704 . This method permits early detection of potential resource shortages in the collection gateway  626 . An alternative to this step  704  is for the CALEA feature server  614  to directly assign collection gateway resources when a subject call is answered. Resources may include circuits and multicast bearer and signaling streams.  
     [0062] The CALEA feature server  614  instructs the Call Control Server  612  to add the specified subject to its surveillance list. Any signaling related to the subject will be replicated and sent to the CALEA feature server  614 , step  706 . An alternative approach to this step  706  is to assign a multicast group (address) for all intercept signaling. The CALEA feature server  614  would be a receiving member of this group. The CALEA feature server  614  also adds the subject to the surveillance list in other servers such as the profile server  620 , the mobility server  616 , the location server  618 , and other feature servers  624 .  
     [0063] At step  708 , the subject, wireless subject  630 , originates a call to a party, participant-C  632 , on the circuit switched public network (P-C). The radio access network  608  sends the origination to the call control server  612  for proper further processing, step  710 . The call control server  612  recognizes that the origination is a member of the surveillance subjects list and replicates the message to the CALEA feature server  614 , step  712 . The CALEA feature server  614  collects the call id, source and destination party ids and the cell location required for signaling to the intercept access point  628 . The cell id may be used to collect coordinate location information from the location server  618 .  
     [0064] At step  714 , the call control server  612  forwards the origination to the bearer distribution network  602  with access to the PSTN  606 . The bearer distribution network  602  signals an origination (e.g. IAM) to the participant-C  632  across the public switched telephone network  606 , step  716 . The terminating party, participant-C answers, step  718 , and the answer is forwarded to the call control server  612 , step  720 .  
     [0065] Noting the call is for a surveillance subject, the call control server  612  assigns multicast addresses for the bearer stream terminations between the radio access network  608  and the bearer distribution network  602 . A circuit termination is associated with the streams for delivery of information to/from the participant-C  632 .  
     [0066] The call control server  612  informs the CALEA feature server  614  of the answer so that that interception by the collection gateway  626 /intercept access point  628  may be enabled, step  724 . The CALEA feature server  614  performs a proxy announcement (e.g., Service Access Point (SAP)) of the multicast sessions established for the subject communications, step  726 . The multicast client in the collection gateway  626  recognizes the announcement is for a session it was earlier instructed, by the CALEA feature server  614 , to listen for. It enables reception of the subject&#39;s IP datagrams from the radio access network  608 , step  728 . The multicast client enables reception of the subject&#39;s IP datagrams from the bearer distribution network  602 , step  730 .  
     [0067] The CALEA feature server  614  signals a call content pen instruction to the collection gateway  626 , step  732 . The subject identity, timestamp, call id, and other required parameters are provided. The collection gateway  626  forwards the open to the intercept access point  628 , step  734 .  
     [0068] The CALEA feature server  614  requests detailed location information of the subject from the location server  618 , step  736 . The location server  618  requests updated location information from the radio access network  608 , step  738 . The radio access network  608  returns the current subject location, step  740 . The location server  618  formats and forwards the response to the CALEA feature server  614 , step  742 .  
     [0069] The CALEA feature server  614  includes the collected location coordinates in an Answer sent to the collection gateway  626 . Also included is the CASE ID and all collected information from the call set up signaling, step  744 . The collection gateway  626  forwards this to the intercept access point  628 , step  746 . At this point the collection gateway  626  captures the call content to and from the wireless subject  630  and sends it to the intercept access point  628 . Any subject related signaling in the network is forwarded to the CALEA feature server  614 , which sends the appropriate signal to the intercept access point  628  as required, step  748 .  
     [0070] It will be appreciated that in this embodiment of the invention does not require the signaling entities (e.g., control/feature servers) to replicate signaling since designated intercept parties signaling may utilize one or more known multicast addresses/ports. Use of separate addresses enables wholesale special treatment such as encryption, which might not be done on normal calls. Further still, calls such as mobile-to-mobile calls or PDG do not have to go through the relay client (e.g. relay client  24 ) or an MCU. It will be further appreciated that the SDU could be incorporated into the radio access network, e.g., into the base transceiver stations of the CDMA cellular communication network.  
     [0071] This embodiment of the invention also enables the use of multicast and signaling related to joining multicast groups. The join may be provided by a multicast client function adapted to the CALEA feature server, which joins the individual&#39;s multicast group when it is announced, e.g., via SAP. However, this may not be required since the CALEA feature server, e.g., CALEA feature server  614 , can do an MGCP Add of the subject&#39;s multicast bearer streams to the circuit (or packet) connection to the intercept access point  628 .  
     [0072]FIG. 11 illustrates a communication network  1100  similar in configuration to that shown in FIG. 1, and like elements are identified using a reference numeral beginning with the number “ 11 .” For example, core network  10 , in FIG. 1, is shown as core network  1110  in FIG. 11. As shown in FIG. 11, the core network  1110  includes a services agent  1102  that interfaces with the services client  1120 . In a preferred embodiment of the invention, the services agent  1102  contains a menu of interception features, such as have been described herein, which can be applied to an intercept order from an authorized LEA. As will be described, the services agent  1102  permits regional variations of intercept requirements to be applied to different targets within a single network using a common equipment design. For a given target and corresponding agency, specific bearer delivery interfaces and event record formats can be selected, simultaneously, within a single network configuration. For example, a single target circuit switched call may be monitored by two LEAs, e.g., LEA  1125  and LEA  1140 . For example, LEA  1140  may require a circuit switched interface, e.g., interface  1141 , for bearer traffic and a signaling interface, e.g., interface  1143 , for signaling information such as TIA J-STD-025 event records. LEA  1125 , however, may require a single packet data interface, e.g., interface  1141 , for the delivery of both bearer traffic and signaling information such as ETSI EN 201 671 event records. Furthermore, home network based interception is required by many governments in addition to the visited network based interception called out by international standards.  
     [0073] In accordance with a preferred embodiment of the invention, the services agent  1102  includes a data structure associated with processing capability. Within the data structure, the services agent  1102  maintains a single target list that permits the services agent  1102  to administer both home network based and visited network based surveillance target interception from a single location. The services agent  1102  may further contain a menu of surveillance features and associated logic, from which requesting agencies may select surveillance features to be associated with a surveillance target upon requesting surveillance services.  
     [0074] The services agent  1102  administers initiation of surveillance services. The services agent  1102  associates a surveillance services requester, for example, a requesting LEA  1125  or  1140 , the services requested and a services client associated with the surveillance target, for example, services client  1120 . The services agent  1102  locates existing services clients upon receipt of a service request for the surveillance target, or provides the instantiation of a new services client for a surveillance target upon initial attachment of the surveillance target to the network. Within the data structure, the services agent  1102  further maintains the list of intercept features and agency delivery addresses for each surveillance target.  
     [0075] In accordance with preferred embodiments of the invention, the services agent  1102  instructs the services client  1120 , or potentially passes appropriate logic to the services client  1120 , to gather the appropriate surveillance features from the CALEA feature server  1126  for application against a specific surveillance target and for a specific LEA. Multiple features can be activated against the surveillance target simultaneously. Since the services agent&#39;s function locates or creates services clients, there is minimal signaling impact to the system when the intercept target list is integrated into the services agent  1102 .  
     [0076] As will be appreciated, this approach combines home and network based interception into a single, unified approach as a home services client is established for a surveillance target even when the surveillance target has roamed into another network. The intercept feature loaded onto the CALEA feature server  1126  will determine the type of interfaces, for example, interfaces  1141 ,  1142  and/or  1143 , used for delivery, and the format of the information delivered. ETSI and TIA standards, as well as custom regional variations are defined as features on the CALEA feature server  1126 , and assigned to each target on the services agent  1102 . The CALEA feature server  1126  communicates with the appropriate gateways via links  1127 ,  1145  and/or  1147 . Various formats and interfaces for specific agencies can be applied to a single or multiple surveillance target simultaneously.  
     [0077] The invention has been described in terms of several preferred embodiments, which are intended to be illustrative of the broad aspects of the invention. It will be understood that the invention is not limited in scope to the preferred embodiments described herein, but instead is limited only by the scope of the subjoined claims.