MXPA01000678A - Method and apparatus for monitoring telephone calls - Google Patents

Abstract

A method and apparatus for monitoring voice and data telephone calls by a law enforcement agency, wherein separate monitoring connections for each party to the call are established. Upon determining (108) that a particular call is to be monitored, the group switch attempts (112) to establish a plurality of separate connections between each multiple point (MUP) on the group switch that receives voice or data signals from one of the parties to the call and one or more monitoring centers. If the connection associated with the primary party to be monitored fails (114), the group switch reroutes signals (124) received from the primary party to a successful connection of the plurality of attempted connections.

Description

METHOD AND APPARATUS FOR MONITORING TELEPHONE CALLS BACKGROUND OF THE INVENTION Technical Field of the Invention The present invention relates to the monitoring of telephone calls by public agencies for compliance with the law and, in particular, to the selection of a preferred connection between a monitoring center and one of the parties in a monitored phone call. Description of Related Art It is well known in the art for public agencies for law enforcement to branch telecommunications junction circuit connections for the purpose of monitoring voice conversations and data transmissions (calls). Telecommunications switches are programmed in the xed with a stored list of telephone numbers assigned to subscribers whose calls are to be monitored. Whenever a group switch handles a call connection having a calling party or an identification number of the called party corresponding to a number in the stored list, the group switch establishes a connection (comprising the "branch"). ") with a monitoring center- The voice or data signals of the group on the side of the calling party are monitored using a first switch connection, while the monitoring of the voice or data signals on the side of the called party requires a second switch connection. Typically, if the request for the establishment of the branch is granted, the group switch routes the first and second switch connections to a collective communication device, which mixes the signals of the first and second switch connections. The group switch then establishes an individual connection to the monitoring center on which the mixed signal is routed. The monitoring center receives the mixed signal and transmits it to a recording device or certain type of monitoring sensor. In some cases, it is desired to establish two or more separate branch connections in the monitoring center (ie a connection for each of the parties). In this case, when a switch handles a call connection that has a calling party or an identification number of the called party corresponding to a number in the stored list, the switch establishes a first connection to the monitoring center for the side of the calling party and a second connection to the monitoring center for the called party's side of the communication. The monitoring center transmits these connections to separate recording devices or monitoring sensors. This provision allows the public body for law enforcement, for example, to easily distinguish which signals originate from each of the parties. In existing monitoring systems those that use the two connection scenarios, however, sometimes problems arise with the establishment of one of the two connections. For example, the connection request may fail, because the number of the particular monitoring center to which the switch directs the connection request or because there is a malfunction in the telecommunications network or in the monitoring center is occupied. In this way, a connection is established for one of the parties, but not for the other. When one of the connection requests fails in this way, the remaining connection or connections are in decline, and none of the parties to the conversation or data transmission is monitored. There are situations, however, in which you want to continue monitoring the signals that originate from one of the parties even when it is not possible to monitor another party. Thus, there is a need for a method and system to maintain a monitoring connection to a call and to allow monitoring of one of the selected parts when a second monitoring connection to the call fails.

PREVIOUS ART The present invention comprises a method and apparatus for monitoring a call connection through a particular body for law enforcement involving the reselection of a monitoring junction circuit to provide monitoring of a primary party to a call connection . According to the invention, a list of subscriber numbers that these subscribers dial into a telephone network whose calls are monitored and stored in a network switching node. Each time a call establishment request is received at the switching node, the calling party and the subscriber numbers of the called party in the request are compared with the stored list of "marked" subscribers. When a call set-up request is received that involves one or more "dialed" subscribers, the call is identified as a call to be monitored. A group switch that is maintaining the call connection attempts to establish separate connections with a monitoring center for each of the parties to the call to be monitored. Generally, the data or voice transmissions of each of the parties to the call are received by the group switch at a particular multiple point (MUP). By establishing a connection between the particular MUP associated with each part of the call and a respective monitoring center, each part can be monitored separately. This ability to separately monitor the parts is particularly valuable in the case of data transmissions, where it is often difficult to distinguish the source of a data transmission if the transmissions of the parties are mixed in an individual monitoring connection with the monitoring center . In some cases, however, one of the separate attempted connections fails. There are two methods for addressing this problem in accordance with the present invention. In the first method, a determination is made as to what part is the primary part to be monitored. The primary part is determined according to the preselected criterion stored in the switching node. Once a failure of one of the multiple tried connections is detected, it is determined if the connection of the primary part is the failed connection. If not, successful connections are maintained and those portions of the call associated with the successful connections including (signals received from the primary party) are monitored. If the primary party connection has failed, however, the group switch reroutes the signals from the primary party to a successful connection. Accordingly, a new connection within the switch is established by connecting the MUP of the primary part with a successful connection between the group switch and the monitoring center, and monitoring of the primary part is provided. In the second method to deal with a failed connection, it is first determined which part of the call is the primary part according to a preselected criterion. The signals received in the MUP associated with the primary part are then routed to the first successful connection between the group switch and the monitoring center. Again, monitoring of at least one primary part is provided. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention reference is made to the following detailed description taken in conjunction with the accompanying drawings in which: FIGURE 1 is a block diagram of a portion of a telecommunications network for establishing connections of calls and to monitor selected call connections through a public body for law enforcement; FIGURE 2 is a block diagram of a switching node in a telecommunications network illustrating a method for separate monitoring of each part of a call connection; FIGURE 3 is a block diagram of the switching node of FIGURE 2 where one of the separate monitoring connections has failed; FIGURE 4 is a block diagram of the switching node of FIGURE 3 wherein the signals received from part A of the call connection has been rerouted to a second successful connection in response to a failure of a first connection of monitoring; FIGURE 5 is a flowchart of a method for reselecting a monitoring connection to provide monitoring for a primary party to a call connection in accordance with a preferred embodiment of the present invention; and FIGURE 6 is a flow chart of an alternative method for establishing a monitoring connection in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION Reference is now made to the Drawings in which similar reference characters represent similar or similar parts throughout the various Figures. Referring now to FIGURE 1, a block diagram of a portion of a telecommunications network 10 including a plurality of switching nodes 12 interconnected by communication link circuits 18 is shown. The communication junction circuits 18 carry voices and data signals between the various communication nodes 12. Although only three switching nodes 12 are shown, it will be understood that network 10 probably includes many more switching nodes. It will also be understood that the network 10 may be a cellular telephone network or a public switched telephone network (PSTN). Each switching node 12 includes one or more group switches 16 which routes the calls through the network. It is now assumed that a call originates with a subscriber station 14 (1) of the calling party (part A), which may comprise either a cellular subscriber station (not shown) or a cable-operated subscriber station ( shown). In addition, the call may comprise a data call, such as a fax or modem connection, or a voice call. It is further presumed that the call has been dialed to the subscriber number of a subscriber station 12 (2) (party B) of the called party, who may also comprise either a cellular subscriber station (shown) or a subscriber station cable-operated (not shown) the call is delivered to a first switching node 12 (1) by means of a connection 26 operated by cable or radio, the network 10 is completely routed through the communication junction circuits 18 by a plurality of group switches 16 at the switching nodes 12, and finally, it is routed to the subscriber number of the subscriber station 14 (2) of the called party. A call connection between part A and part B is established with this. Public agencies for law enforcement are often authorized to monitor telephone calls to obtain evidence to be used in criminal investigations. To achieve this goal, a monitoring center (MC) 28 is established which may include one or more tape recorders (R) 30 or other monitoring devices to record or detect the voice conversation or data transmission that is being monitored. monitored The physical connection to the voice portion of the telephone network 10 that allows monitoring is done through a branch (generally shown at 34) where the signals are routed through a communication junction circuit 48, through a switching node 12 (4), and up to a monitoring center 28 via a connection 26. The communication link circuits 48, the switching node 12 (4), and the connection 26 provide varied voice and data communication paths used to carry communications from the subscriber station 14 to the monitoring center 28 and the recorders 30 therein. The branch 34 can be made at any location within the telephone network 10 in a manner well known to those skilled in the art, although typically it is done through a request from one or a few of the switching nodes 12 connected to the subscriber in a network operated by cable or where the subscriber being monitored is currently located (roaming) in a cellular network. The monitoring center 28 of the public body for compliance with the law uses the branch 34 to monitor the communication (which can be recorded by the tape recorder 30 for future use). Each switching node 12 is programmed with a stored list (L) 50 of subscriber numbers for those subscribers whose calls are to be monitored by a public body for compliance with the law. When a switching node 12 handles a local branch of a call and a calling party or a called party identification associated with that local branch may correspond to an entry to a stored list 50, the group switch 16 handling the call transmits a request for a branch connection 34 to the monitoring center 28. Referring now to FIGURE 2, a block diagram of a switching node 12 (1) connecting a subscriber station 14 (1) of the calling party to a subscriber station 14 (2) of the party is illustrated. call, where one of the parties is marked to be monitored (that is, a dialed subscriber). Although only one switching node 12 (1) and one group switch 16 are shown, it will be understood that the call connection between the subscriber station 14 (1) of the calling party and the station 14 (2) of the party The call will generally be routed through a plurality of switching nodes 12, and group switches 16 contained therein, located in one or more networks 10. Group switch 16 includes a plurality of multiple points (MUPs). to receive incoming communication signals for a subscriber station 14 either from another switching node 12 via one of the communication link circuits 18 or from one of the connections 26 in a switching node 12 which is connected to a station 14 of subscriber. Each of the parts for a call connection is associated with a particular MUP 20 in the group switch 16. The voice or data communication signals originate from the subscriber station 14 (1) of the calling party are received by the group switch 16 in a first MUP 20 (1), while the communication signals that originate from the subscriber station 14 (2) of the called party are received by the group switch in a second MUP 20 (2). By establishing a connection between each MUP 20 and an MC 28, a call associated with the particular MUP 20 can be monitored. -To facilitate this monitors, the switching connections 22 (1) and 22 (2) are established with the first and second MUPs 20 (1) and 20 (2) to connect the branch 34 so that both sides of the conversation or communication can be monitored. Each switching connection 22 can then be connected to the corresponding MC 28 on branch ~ 34 for purposes of monitoring the call connection. The operation of the group switch 16 according to the present invention will now be discussed in more detail.

Upon receipt of a call set-up request at the source switching node 12 (1), the number of the part A and the number of the part B are compared individually with the stored list 50. If a match exists, then a switching controller 24 at the switching node 12 (1) notifies the group switch 16 that is handling the call that the call is to be monitored. As a result, the group switch 16 attempts to establish a first branch connection 34 (1) between the first MUP 20 (1) and a first MC 28 (1) to monitor the subscriber station 14 (1) of the -part A and a second branch connection 34 (2) between the second MUP 20 (2) and a second MC 28 (2) to monitor the subscriber station 14 (2) of the part B. A recording device 30 in each MC 28 it then records the signals received through each of the branch connections 34 (1) and 34 (2). When two or more branch connections 34 are established, one of the connections is then referred to as the primary connection, while the connection or the retentive conditions are the secondary conditions. In most cases, the primary connection is the part whose subscriber number has been marked for monitoring. In many monitoring systems, the switching connections 22 (1) and 22 (2) are mixed together in an individual connection that transmits both sides of the call connection that is established between the group switch 16 and the MC 28. Al establish two separate connections, however, each part can be monitored separately, and it is much easier to distinguish between the signals originating from the subscriber station 14 (1) of the calling party and the signals originating from the station 14 (2) and subscriber of the called party. Further, although the branch connections 34 for the separated MCs 28 are shown for illustrative purposes, it will be understood that, in a preferred embodiment, the first branch 34 (1) and the second branch 34 (2) is made for an individual MC 28 . Branches 34 (1) and 34 (2) can then be routed to different recording devices 30 on the MC 28 to monitor each term of the communication or they can be routed to an individual recording device 30, assuming a record is kept from being recorded. portions of the signals are received from each of the respective connections. It should be noted that a call connection can involve more than two parties. In such a case, a separate connection can be established for each of the multiple parties. In the alternative, signals from some of the parts can be combined. For example, a first branch connection 34 (1) can be established for the dialed subscriber, while the other parts of the call are combined in a second branch connection 34 (2). Assuming that both or all of the attempted branch connections 34 are successful, the use of separate connections has substantial benefits. In practice, however, one of two or more branch connections 34 between the MC 28 and the group switch 16 sometimes fails. When such failure occurs in current systems, the successful connection or connections are typically automatically terminated. In this way, none of the communication parts can be monitored. According to the method and system of the present invention, a successful branch connection 34 between the group switch 16 and the MC 28 is maintained even if another of the required connections fails. In addition, with the failure of one of the branch connections 34, the state of the successful connection and the failed connection is evaluated to determine a preferred (or primary) part for monitoring purposes. The criterion in which the preferred part is determined depends on what portion (ie, side) of the communication from the public body for compliance with the law anticipates being the most important or useful. For example, the criterion can select according to the preferred part the part whose subscriber number is marked for monitoring. Alternatively, the criterion may select according to the preferred part the part of the monitored communication that is transmitting (ie, of origin) a facsimile or a certain type of data transmission. On the other hand, the criterion of the preferred party may differ for different types of communications. The preferred part may vary, for example, between calls that come out against incoming calls, voice calls against data calls, or fax calls against other types of data calls, or the criterion may select the preferred part according to a certain combination of these various exemplary distinctions. In cases where there are more than two parties to a call connection (for example, a collective conference), more sophisticated selection criteria may be necessary. In a situation where there are three parties (a calling party and two called parties), for example, the criterion must account for the possible failure of one or two connections. In other words, if a connection out of three attempted connections fails, the criteria must specify which of the two parties is preferred. Similarly, if two connections fail the criterion must specify which part, of the three attempted parts is preferred. Generally speaking, an algorithm for determining the preferred part according to the desired criterion is stored in a memory in the switching controller 24, and a software in the switching controller 24 uses the stored algorithm to select the preferred part when one of the connections fails. The switching controller 24 then directs the group switch 16 to route the signals received in the MUP 20 associated with the preferred part of the successful connection. The monitoring system of the present invention, therefore, allows public agencies for law enforcement to obtain the benefits of obtaining a separate connection for each part of a call without risk of loss of all monitoring capabilities if one of the branch connections 34 fails. In addition, the system allows the agency to select which part is monitored in the event that one or more of the connections fail. With reference to FIGURES 3 and 4, a block diagram of a group switch 16 is illustrated, respectively, in an initial attempt to establish two separate connections with the MCs 28 and a block diagram of a group switch 16 where the switching connections 22 have been reselected in the connection fault. It is assumed that a call setup request has been received from a subscriber station 14 (1) of the calling party to establish a call connection with a subscriber section 14 (2) of the called party. On the other hand, it is assumed that the switching controller 24 has determined that the calling party is a dialed subscriber and has directed the group switch 16 to establish a branch 34 of the call connection, as discussed in the foregoing. Accordingly, with reference now to FIGURE 3, the group switch 16 attempts to establish a first branch connection 34 (1) between the first MUP 20 (1) and a first MC 28 (1) to monitor the station 14 (1). ) subscriber of the calling party and a second branch connection 34 (2) between the second MUP 20 (2) and a second MC 28 (2) to monitor the subscriber station 14 (2) of the called party. However, the first branch connection 34 (1) fails (as indicated generally at 42), while the second branch connection 34 (2) is successful. After conducting an investigation of the preferred part, the switching controller 24 determines that the calling party is the primary (preferred) party and that the called party is the secondary party. Therefore, monitoring of subscriber station 14 (1) of the calling party on the successful connection is desired. With reference now to FIGURE 4, the path of the switching connections 22 within the group switch 16 is reselected in response to the failed connection of FIGURE 3. Accordingly, while maintaining the branch connection 34 (2), the first connection 22 (1) it is redirected (as generally indicated at 44) to join the first MUP 20 (1) with the second branch connection 34 (2), and the second switching connection 22 (2) is redirected to join the second MUP 20 (2) ) with the first branch connection 34 (1) failed. Alternatively, the second switching connection 22 (2) is simply falling. In any case, the reselection of the switching connections 22 establishes a branch 34 to the MC 28 so that the primary part can be monitored. Referring now to FIGURE 5, a flow diagram of a method 100 for reselecting switching connections according to a preferred embodiment of the present invention is illustrated. In an initial stage 102, a call setup request is received by the switching node 12. The group switches 16 in the switching node 12 route the call according to the portion of the called party number of the call set-up request in step 104, and a call connection is established in step 106. With the reception of the call set-up request and consequently with step 104, a determination is made in step 108 as to whether calls from subscriber station 14 (1) of the calling party, or calls to the station 14 (2) of the subscriber of the called party, will be monitored by a public body for compliance with the law. If not, the process ends in step 110. However, if any part is marked to be monitored, separate one-way connections are attempted in step 112 from a MUP 20 (1) associated with station 14 (1) subscriber of the calling party to an MC 28 and from a MUP 20 (2) associated with the subscriber station 14 (2) of the called party. Then, in step 114, any of the failed attempted connections is determined. If both of the connections are achieved, separate monitoring of each part is performed in step 116. If one of the connections fails, a set of criteria of the preferred part is examined in step 118 to determine which of the parts of the Call is the preferred call. Then, in step 120, it is determined whether the initial connection attempt with the preferred part was successful. If the connection to the preferred part was successful, then, the monitoring of the preferred part occurs in step 122. On the other hand, if the connection with the preferred part fails, the reselection of the switching connections occurs in step 124 of So that the voice and data communications of the preferred part is routed back to the successful MC connection, and monitoring of the preferred part then occurs in step 122. Referring now to FIGURE 6, a flow chart is illustrated of an alternating method 200 for selecting switching connections according to an alternative embodiment of the present invention. A call set-up request is received by a switching node 12 in an initial stage 202; the group switches 16 in the switching node 12 route the call according to the portion of the called party number of the call set-up request in step 204; and a call connection is established in step 206. Upon receipt of the call set-up request and consequently with step 204, a determination is made in step 208 as to whether the call is to be monitored, if not , the process ends in step 210. If any part is marked to be monitored, multiple separate single-way connections are attempted from the group switch to an MC 28 in step 212. However, instead of associating each attempt for connection to a particular part, each connection attempt is not initially connected (for example, by switching connections 22 as in the preferred 1Q0 method) to any part of the call. Then, a set of criteria of the preferred part is examined in step 214 to determine which part of the call is the preferred part. In step 216, the attempted connections are monitored to determine which one happens first. The signals of the preferred part are routed to the first successful connection by establishing a switching connection 22 in step 218, and monitoring of the preferred part begins in step 220. The signals of the remaining part or parts are routed to the next successful connection (or connections) in step 222, assuming that another successful connection exists and separate monitoring of the remaining part begins in step 224. Although a preferred embodiment of the method and apparatus of the present invention is illustrated in the accompanying Drawings and described in the above Detailed Description, it is understood that the invention is not limited to the described mode, but is capable of numerous arrangements, modifications, and substitutions without departing from the spirit of the invention as established and defined by the following claims.

Claims (31)

1. A method for monitoring a telephone call connection by a public body for law enforcement, comprising the steps of: determining that a call between a plurality of parties is to be monitored; try to establish, in response to the determination, a plurality of connections with a monitoring center to monitor the plurality of parts; detect a fault to establish at least one of the attempted connections; and reroute the communications received from the failed connection to a successful connection attempted in response to the detection of a failed connection.

2. The method of claim 1, further comprising the step of selecting a preferred part for monitoring. The method of claim 2, wherein the step of detecting a failed connection comprises detecting a failure by establishing a connection between the preferred part and the monitoring center. The method of claim 3, wherein the step of re-routing the communications comprises re-routing the received communications from the preferred part to a successful one of the attempted connections. The method of claim 2, wherein re-routing the communications further comprises the steps of: disconnecting a portion of a successfully connected junction circuit that connects the monitoring center and one of the parties to the monitored call; restore a new path of the junction circuit, where the new path connects the monitoring center and the preferred part. The method of claim 5, wherein disconnecting a portion of the successfully connected junction circuit includes disconnecting an internal connection in a group switch. The method of claim 2, wherein the call to be monitored comprises a data call. The method of claim 7, wherein the step of selecting comprises the step of automatically selecting as the preferred part a part that is a source of a data transmission. The method of claim 2, wherein the step of selecting a preferred part further comprises the step of evaluating a set of criteria of the preferred part to select a preferred part of the plurality of parts. The method of claim 1, wherein the plurality of connections attempted comprises a separate attempted connection for each of the plurality of parts. The method of claim 1, wherein the step of attempting to establish a plurality of connections comprises transmitting a call setup request to establish a call between a switching node through which the call to be monitored is routed and the monitoring center. 12. A method for monitoring a telephone call connection by a public body for compliance with the law, comprising the steps of: determining that a call between a plurality of parties is to be monitored; try to establish a plurality of connections with a monitoring center to monitor the plurality of parts; select a preferred part to monitor; and establish a connection between the preferred part and the monitoring center over a successful first part of the attempted connections. The method of claim 12, further comprising the step of establishing a connection between a second of the plurality of parts and the monitoring center on a successful second of the attempted connections. The method of claim 12, wherein the call to be monitored comprises a data call. The method of claim 14, wherein the step of selecting comprises the step of automatically selecting as the preferred part a part that is a source of a data transmission. The method of claim 12, wherein the step of selecting a preferred part further comprises the step of evaluating a set of criteria of the preferred part to select a preferred part of the plurality of parts. 17. The method of claim 12, wherein the plurality of connections attempted comprises a separate attempted connection for each of the plurality of parts. The method of claim 12, wherein the step of attempting to establish a plurality of connections comprises transmitting a call setup request to establish a call between a switching node through which the call to be monitored is routed and the monitoring center. 19. A system for monitoring a telephone call through a public body for compliance with the law, comprising: at least one monitoring center to monitor a call connection; and a switch to establish the call connection between a subscriber to be monitored and at least one other subscriber to a telecommunications network and to establish a plurality of monitoring connections to at least one monitoring center, such signals to return to routing the received switching from a preferred subscriber to a successful monitoring connection with at least one monitoring center in failure of a monitoring connection between the subscriber's preferred and at least one monitoring center. The system of claim 19, further comprising a memory for storing information identifying the subscriber to be monitored. The system of claim 19, further comprising a switching controller for selecting the preferred subscriber according to the stored selection criteria. The system of claim 19, wherein the switch includes a plurality of multiple points (MUPs), each subscriber in such connection associated with a particular MUP. The system of claim 22, wherein each of said monitoring connections comprises: an external connection between the switch and the monitoring center; and an internal connection within such a switch, such an internal connection connecting the external connection to a MUP associated with one of the subscribers in the call connection. The system of claim 23, wherein the switch reroutes the internal connection connected to the MUP associated with the preferred subscriber in failure of the external connection for the preferred subscriber, by routing a successful external connection. 25. A system for monitoring a telephone call through a public body for compliance with the law, comprising: at least one monitoring center to monitor a call connection; and a switch to establish said call connection between a subscriber to be monitored and at least one other subscriber to a telecommunications network and to establish a plurality of monitoring connections to at least one monitoring center, such signals to route the switching received from a preferred subscriber to a successful monitoring connection with at least one monitoring center. 26. The system of claim 25, further comprising a memory for storing information that identifies the subscriber being monitored. The system of claim 25, further comprising a switching controller for selecting the preferred subscriber according to the stored selection criteria. The system of claim 25, wherein said switch includes a plurality of multiple points (MUPs), each subscriber in such connection associated with a particular MUP. The system of claim 28, wherein each of said monitoring connections comprises an external connection between the switch and the monitoring center, the system further comprising an internal connection within such switch, such internal connection connecting the external connection to a MUP associated with one of the subscribers in the call connection. 30. The system of claim 29, wherein the internal connection connected to the MUP associated with the preferred subscriber is routed to a first successful external connection. The system of claim 30, wherein the internal connection connected to the MUP associated with a second of the subscribers is routed to a second successful external connection.