Abstract:
Monitored calls are intercepted and rerouted to a changed location number of a called party while appearing to be at the same directory number by intervention of an IP Address Mapping check Point (IP-AMCP) which duplicates the voice to a monitoring location, automatically identifies the types of networks to be traversed to the new location and adapts the duplicated voice message to traverse such network types. Surveillance is enabled to be conducted at more than one monitoring location each of which many are widely separated from the other.

Description:
FIELD OF THE INVENTION 
     This invention relates to surveillance of telephone calls over a public communications link and is particularly concerned with providing assistance for such surveillance to law enforcement agencies. It particularly concerns surveillance of voice over IP (i.e., VOIP) (e.g., cable) networks. 
     BACKGROUND OF THE INVENTION 
     Requirements for enabling surveillance of electronic communications have been enacted into public law (e.g., Public Law 103-414 enacted Oct. 25, 1994 CALEA Communications Assistance for Law Enforcement Act) reciting requirements for assuring law enforcement access to electronic communications. Such access is required to be in real time, have full time monitoring capabilities, simultaneous intercepts, and feature service descriptions. The requirements specifically include capacity requirements and function capability. It is incumbent upon communication carriers to provide such capability and capacity. 
     While initially limited in scope, at present, to certain communications technology it is almost assured that it will be extended to new forms of communication. New technologies require extension of CALEA to the new phone system technologies. 
     In IP telephony the location of a called party may be dynamic and in motion. It may be desirable to monitor a called party IP telephone even as the location of that phone changes. It may also be appropriate to allow a calling party to remain unaware of the new DN. 
     SUMMARY OF THE INVENTION 
     Monitored calls are intercepted and rerouted to a changed location/directory number of a called party while appearing to the caller to be at the same directory number, in accord with the principles of the invention, by intervention of an IP Address Mapping check Point (IP-AMCP) which duplicates the voice to a monitoring location, automatically identifies the types of networks to be traversed to the new location and adapts the duplicated voice message to traverse such network types. Surveillance is enabled to be conducted at more than one monitoring location each of which many are widely separated from the other. 
     In a particular illustrative embodiment an authorized surveillance agent transmits a valid request to an IP Address Mapping Check Point (IP-AMCP) which in response intercepts voice packets to and from the targeted IP phone. The duplicated voice packets are transmitted to the designated monitoring location. The IP-AMCP determines the type of voice signal to be transmitted to the terminal monitoring station. If the monitoring location is serviced by an IP telephony network the monitored traffic is duplicated by the IP-AMCP in IP format to an IP Directory Number (DN) as programmed in accord with an IP Phone Intercept List (IP-PIL). If the monitoring location is serviced by a PSTN network a PSTN Check Point (PSTN-CP) establishes a trunk connection with the Local Digital Switch (LDS) and receives incoming voice packets at the IP-AMCP which the PSTN-CP converts to Time Division Multiplex (TDM) voice and uses a trunk (i.e., T 1 ) to communicate with the LDS. 
     A further arrangement allows a caller to call an original number of a changed DN being monitored with surveillance transferred to a new DN of the called party (i.e., the victim) at a new physical location. In this mode the IP-AMCP intercepts the call and queries the IP-PIL for new delivery instructions such as the new destination PSTN or IP phone number. 
     If the new call transferred to the IP DN needs to be protected, the surveillance agent can remotely turn on an “address masking” feature on the IP-AMCP. Once the feature is activated, the called party&#39;s new DN (i.e., calling ID) is replaced with the original DN therefore the call being made appear as the same destination location to the caller. 
     If the call is initiated from an IP network to a subscriber transferred from IP telephone service back to PSTN network service or vice versa, the IP-PIL query result is used by the IP-AMCP to notify the PSTN-CP to make a new a connection to the Local Digital Switch (LDS) 
     If the call is initiated from an IP network to an IP phone user at a new IP location, the IP-PIL query result is used by the IP-AMCP to route the call to the new IP location. 
     If the call is initiated from the PSTN to an old IP phone user at a new PSTN location the IP-AMCP first intercepts the call, queries the IP-PIL and notifies the originating LDS to establish connection with the new destination LDS directly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a block schematic of a network encompassing the invention principles to dynamically route packets for surveillance purposes and to mask the terminal directory numbers of the routing; and 
     FIG. 2 is a flow graph explaining the process of the network is operating the system of FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     A surveillance system for monitoring calls received by a called party at a receiving station which may change its Directory Number (DN) or its location or its telephone technology, provides for monitoring traffic that the receiving station receives from a calling party whose interactions is to be monitored. This surveillance system, as shown in the FIG. 1, permits a monitored called party to move and dynamically routes calls to be monitored to the new location, Directory Number (DN) and accommodates new telephone technologies that may be encountered in processing the call. 
     A monitoring station  101  is shown connected to an IP backbone  103 , via an Hybrid Fiber Coax (HFC)  105  connected to the IP backbone network  103 . HFC is a connection technology having optic fiber connected to the IP backbone network and a coaxial cable connected to the terminal stations. An electro/optical connection joins the optical fiber and coaxial cable. It allows for increased overall broadband services/capacity to be supplied the terminal station. 
     The receiving caller whose calls are to be monitored is shown as probably connected to its old location at station  111 , or at station  115 , both of which share the same original DN and both of which are connected to the IP backbone network  103  via the HFC distribution plant  105 . Originating station (i.e., caller)  113  is masked from identifying the actual DN and location of the recipient of the calls. Station  111  has been terminated, however this termination is to remain transparent to the caller. Station  115  having the same DN is at a different location. Receiving station  115  connected to the IP backbone network  103  has a new IP DN (i.e.,DN-1) assigned. Yet another receiving station  117 , having a new PSTN DN (DN-2) is shown connected, via a Local Digital Switch (LDS)  121  to a Public Switched Telephone Network.(PSTN)  107 . Trajectories  131  and  133  show the migration of the old monitored station  111  to locations now represented by the DN-1 and DN-2. 
     IP backbone network  103  includes an IP Address Mapping Check Point (IP-AMCP)  141  which duplicates the voice of a monitored station and transmits it to a monitoring location for surveillance and automatically identifying the types of networks to be traversed in such a transmission and adapts the voice message to such a network type to permit communication with monitoring stations connected to different type networks. It also provides masking of the called DN and may deliver the original old DN to the caller&#39;s station  113 . 
     The IP-AMCP may be embodied in a server within or connected to the network. It has the capability, through programming, of examining packet contents and authenticating users of the network. With specific WatchDog software the IP- AMCP identifies specific activity from designated telephone stations at a specified DN or IP address and can replicate/duplicate the packets of that phone which replicated/duplicated packets may be forwarded to a monitoring station. 
     An IP Phone Intercept List (IP-PIL)  143  is associated with IP-AMCP  141  and provides the monitored station  101  with the numbers to which the monitoring intercept is connected and provides conversion information for converting the voice signal to conform with the network type of the monitored station. 
     In instances of the monitored station  117  being connected to the PSTN system  107 , the IP-AMCP  141  converts the format of the monitored signal to a PSTN system format. It is connected to the PSTN system  107 , via the PSTN Check Point (PSTN-CP)  145 . PSTN-CP  145  establishes a trunk connection with the Local Digital Switch (LDS)  121  and receives incoming voice packets from the IP-AMCP which the PSTN-CP converts to voice trunk (i.e., T 1 ) to communicate with the LDS  121 . 
     Operation of the surveillance network of FIG. 1 may be ascertained by reference to the flow chart of FIG.  2 . In a system where the telephone of a recipient of calls is monitored, it may be advisable for that recipient to move and perhaps use a new Directory Number (DN). It is desirable that the caller not be aware of the new DN and that calls to the previous DN appear to the caller that the recipient is still at this same location and DN. It is also desirable that the new DN be readily accessible to the inquiring monitor station for purposes of surveillance. 
     The process stars at terminal  201  and as per block  203  a caller initiates a call to the intended recipient at the customary DN. The call request is forwarded via an HFC distribution plant to an IP-AMCP which through an IP-PIL listing intercepts the call as per instructions of block  205 . The called number is detected by DN masking and the IP-AMCP converts the called number to the new DN of recipient, as per instructions of block  207 . 
     In decision block  209  an inquiry determines if this is a call to a recipient connected to the IP backbone network. If such is the case the call is connected to the recipient DN as per block  211  and the surveillance station is alerted, by means of the IP-AMCP, as per block  213 . Surveillance is continued until call is complete a per block  215  and the process ends at terminus  227 . 
     If the decision of block  209  determines that the call is not to an IP DN a subsequent decision of block  217  determines if it is to a PSTN DN. IF not the process is terminated at end  227 . If yes the instructions of block  219  connect the call to an PSNT checkpoint which translates the DN to PSTN form for delivery to the PSTN LDS. 
     The surveillance is alerted as per block  221  instructions and the station is connected via the IP-AMCP to monitor the call. The IP-AMCP replicates the traffic as per block  223  for delivery to the surveillance agent. Surveillance is terminated as per block  225  at the end of the call and the process terminates at terminus  227 . 
     The following applications are being filed concurrently with the present application and are incorporated herein by reference. All applications have the same inventors (e.g., Kung, Russell, Sankalia and Wang): 
     U.S. patent application Ser. No. 09/375,754, filed Aug. 18, 1999, entitled Monitoring Selected IP Voice Calls Through Activity of a WatchDog Program at an IP-Addressing Mapping Check Point; 
     U.S. patent application Ser. No. 09/375,750, filed Aug. 18, 1999, entitled Monitoring IP Voice Calls Under Command of a PSTN Phone; 
     U.S. patent application Ser. No. 09/376,782, filed Aug. 18, 1999, entitled Flexible Packet Technique for Monitoring Calls Spanning Different Backbone Networks; 
     U.S. patent application Ser. No. 09/376,783, filed Aug. 18, 1999, entitled Multiple Rotiiiig and Automatic Network Detection of a Monitored Call from an Intercepted Targeted IP Phone to Multiple Monitoring locations; 
     U.S. patent application Ser. No. 09/376,459, filed Aug. 18, 1999, entitled Secure Detection, of an Intercepted Targeted IP Phone from Multiple Monitoring Locations; 
     U.S. patent application Ser. No. 09/376,454, filed Aug. 18, 1999, entitled IP Voice Call Surveillance Through use of Non-dedicated IP Phone with Signal Alert Provided to Indicate Content of lncoming Call Prior to an Answer as Being a Monitored Call. 
     While exemplary systems and methods embodying the present inventions are shown by way of example, it will be understood, of course, that the invention is not limited to these embodiments. Modifications may be made by those skilled in the art which differ from the specific details disclosed here, but which are still within the scope of the invention. Further elements of one invention may be readily included as elements of one of the other inventions. Those skilled in the art may combine or distribute the elements in many different ways without departing from the spirit and scope of the invention.