WO2005107159A1

WO2005107159A1 - A media control method for realizing the lawful interception by using the soft-switch system

Info

Publication number: WO2005107159A1
Application number: PCT/CN2004/000431
Authority: WO
Inventors: Wei Xu; Yan Tang; Xiaoxia Jiang
Original assignee: Utstarcom Telecom Co., Ltd.
Priority date: 2004-04-29
Filing date: 2004-04-29
Publication date: 2005-11-10
Also published as: CN1926807A; CN100461715C

Abstract

A media control method for realizing the lawful interception includes the following steps : establish the up-shadow-termination corresponding to the intercepted termination in the context of the intercepted termination of the intercepted object, the up-shadow-termination is used to audit the up media flow of the intercepted object ; establish the down-shadow-termination corresponding to the opposite termination in the context of the opposite termination of the intercepted termination, the down-shadow-termination is used to audit the down media flow of the intercepted object ; and bridge the up-shadow-termination, the down-shadow-termination and intercepting termination corresponding to the interception center to the same conference bridge, wherein the up media flow and the down media flow of the intercepted object is mixed on the conference bridge through the up-shadow-termination and the down-shadow-termination. So the present invention realizes the interception function to the intercepted termination.

Description

T N2004 / 000431

Implemented with a softswitch system

Media control method for legal surveillance

The present invention relates to a related technology of a media networking model of a legal monitoring function in a communication network, and in particular, to a method for legal monitoring of media control in a soft switching system. Background technique

Legal interception refers to the requirement that telecommunication operators track and monitor the traffic and non-traffic activities of specific users in real time through user settings according to certain legal procedures. The monitoring content includes the user's location information, power on / off information, call status information, short message sending / receiving content, call content, data communication, and fax content. With the continuous development of communication technology, more and more telecommunications operators require the system to have this function of legal interception.

Softswitch technology is the core technology of the Next Generation Network (NGN). It separates call signaling control and media bearers in traditional switches, and connects and communicates between entities through standard protocols. Call control is separated. The media bearer access, resource control, and management are implemented by the entity MGW (Media Gateway), and the control of the media in the CallServer (call server) is implemented by the entity MGC (Media Gateway Controller). The control interface between the media gateway controller and the media gateway uses standard protocol standards, such as the media gateway control protocol proposed by the IETF (Internet Engineering Task Force): the Media Gateway Control Protocol (MGCP) and the media gateway control developed by the ITU-T Protocol H.248 / Megaco protocol.

The technical specifications of 3GPP (Third Generation Partnership Project) TS33.107-Lawful Interception Architecture and Functions have detailed descriptions of the functional entities that are legally intercepted. Therefore, the implementation scheme of the DF3 function, the media control networking model in CallServer is Key technologies for legal interception. We can N2004 / 000431

To achieve certain media networking through the standard interface protocol between MGC (Media Gateway Controller) and MGW (Media Gateway) under the softswitch system, so that calls can be implemented without changing the call signaling control and using standard media gateways Listening to business.

One of the most simple and easy media networking methods is to use the local conference bridge networking method, as shown in Figure 1. Calling user A initiates a call from its endpoint TA to endpoint TB of called user B. Figure 1 shows the situation where calling user A and called user B are on different gateways. The calling context in which calling user A is located (Call Context) 1 includes an intermediate endpoint TA, and the call context 2 where the called user B is located includes an intermediate endpoint TB, and these intermediate endpoints constitute a path. When calling user A is monitored, that is, in the case where calling user A is the monitored user, the endpoint TA of the monitored user and the endpoint TB of the call user and the legal monitoring endpoint Tm corresponding to the monitoring center are bridged to a conference bridge in conference context 3. In the middle, the mixing function of the conference bridge is used to monitor the media stream after the voices of the monitored user A and his call user B are mixed. Although this networking method is simple, this method changes the networking mode of the monitored call, which affects the media control process of the original ordinary call, and turns the original ordinary call into a multi-party call based on the conference bridge. Operations for ordinary endpoints have become operations for listening to endpoints on the conference bridge. In addition, in this way, the media connection operation for each supplementary service will send different media connection commands as the user is being monitored, forming different media networking models. Such changes will make the media control quite complicated and impossible. accept. Summary of the invention

In view of the above problems, the present invention proposes a media control method for monitoring service implementation. Based on the concept of "shadow endpoint", the monitoring call is attached to the basic call. The "upstream shadow endpoint" and "downlink shadow endpoint" The topological connection between the monitoring object and the call object, so as to obtain the upstream and downstream media streams of the monitored object, and then 1

The "up and down shadow endpoints of the monitored object" and the circuit of the monitoring center are bridged into a conference bridge, and the mixing function of the conference bridge is used to monitor the media stream after the voice mixing of the monitored user and his callee. The networking mode does not change the media topology connection and media control process of any original ordinary calls.

According to another aspect of the present invention, a media control method for implementing legal interception is provided, including the following steps:

1) establishing an uplink shadow endpoint corresponding to the monitored endpoint in the context of the monitored endpoint of the monitored object, where the uplink shadow endpoint is used to listen to the uplink media stream of the monitored object;

2) establishing a downlink shadow endpoint corresponding to the peer endpoint in the context of the peer endpoint of the monitored endpoint, where the downlink shadow endpoint is used to listen to the downlink media stream of the monitored object; and

3) bridging the uplink shadow endpoint with the downlink shadow endpoint and the listening endpoint corresponding to the listening center to the same conference bridge,

The uplink media stream and downlink media stream of the monitored object are mixed on the conference bridge through the IP streams of the upstream shadow endpoint and the downstream shadow endpoint, respectively, thereby implementing the monitoring function of the monitored endpoint.

According to an aspect of the present invention, a media control method is provided, including the following steps:

1) Use the Megaco command Add to establish a listening endpoint corresponding to the monitored call media bearer in a new context;

2) Through the Megaco command Add, add an auxiliary uplink shadow endpoint to the context corresponding to the monitored endpoint where the monitored object is located, which is used to listen to the upstream media stream of the monitored object;

3) Via the Megaco command Add, add an auxiliary downlink shadow endpoint to the context corresponding to the monitored endpoint where the monitored object is located, which is used to listen to the downstream media stream of the monitored object; 31

4) Establish a three-party conference bridge through the Megaco command Add, including a first endpoint, a second endpoint, and a third endpoint for providing services to the outside;

5) Use the Megaco command Add to add a secondary IP point in the context of the listening endpoint and configure the remote IP as the third endpoint;

6) Use the Megaco command Mod to configure the remote IP of the uplink shadow endpoint and the downlink shadow endpoint as the first endpoint and the second endpoint, respectively;

7) The Megaco command Mod is used to disconnect the bidirectional topology connection between the uplink shadow endpoint and the peer endpoint of the monitored endpoint;

8) The Megaco command Mod is used to disconnect the bidirectional topology connection between the downstream shadow endpoint and the monitored endpoint.

The above and other objects, features, aspects and advantages of the present invention will be made clear by the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings provide a further understanding of the present invention, constitute a part of the description, illustrate embodiments of the present invention, and explain the principles of the present invention together with the text description.

Figure 1 is a traditional legal monitoring network model diagram;

Figure 2 is a media control diagram in a media gateway;

FIG. 3 is a network model diagram of a legal monitoring media network according to the present invention; FIG.

Figure 4 is a flowchart of basic call monitoring media control. detailed description

Hereinafter, specific embodiments of the present invention will be described in detail based on the drawings.

Figure 2 is a media control diagram in a media gateway.

As shown in FIG. 2, the media control involved in the present invention uses a soft switching architecture, and call signaling is separated from media control. MGC (Media Gateway Control) implements control of media establishment, MG (Media Gateway) implements specific bearer establishment and resource management control 1

system.

MGC (Media Gateway Control) controls MG (Media Gateway) in accordance with the standard ITU-T protocol Megaco (h.248). A series of standard messages (Add, Subtract Modify) and standard message packages defined by Megaco are used to implement the media networking model described below.

Among them, the termination (Termination) is the generation and / or termination of the media stream; the context (Context) is a set of interconnected series of endpoints. There can be multiple associated endpoints in a context, and this association can be demonstrated by different topological relationships between the endpoints. The method proposed by the present invention makes use of this, and adds auxiliary "shadows" and "endpoints" in the context of the original call, and utilizes the one-way topological connection between the corresponding endpoints and the media bearer of the cause call to implement the monitoring function

According to the h.248 protocol description, MGC's media flow control for endpoints includes modification of endpoint media bearer attributes and modification of topology connection relationships between endpoints.

The endpoint media bearer attribute refers to the media stream sending and receiving attributes of the endpoint, including: SendOnly (receive only), ReceiveOnly (receive only), SendReceive (receive), Inactive (not available), Loop (loopback).

The topology connection refers to the transmission direction of the media stream between two endpoints, including: OneWay (unidirectional), BothWay (bidirectional), Isolate (no media connection).

The call monitoring media control networking model of the present invention makes full use of these two standard media control methods to change the media connection of the endpoints in the MG.

FIG. 3 shows a network model of a legal monitoring media network according to the present invention.

As shown in FIG. 3, the calling user A initiates a call from its endpoint TA to the endpoint TB of the called user B. The situation shown in FIG. 3 is the case where the calling user A and the called user B are at different gateways, and the calling user A The call context 1 in which it is located includes the peer endpoint TA, and the call context 2 in which the called user B is located includes the peer endpoints TB,, endpoints TA, and TB, which are all intermediate endpoints constituting the path. When calling user A is monitored Listening, that is, if the calling user A is a monitored user and the monitored endpoint is TA, the "uplink shadow endpoint" UpT corresponding to its endpoint TA and its peer endpoint TA are added to the context (Context) 1 where the calling user A is located. The corresponding "downlink shadow endpoint" DownT, "uplink shadow endpoint" UpT and "downlink shadow endpoint" DownT are IP endpoints, and the media bearer attribute is SendOnly (send only). "Up Shadow Endpoint" UpT only has a two-way topology connection with the monitored endpoint TA; "Down Shadow Endpoint, DownT only has a two-way topology connection with the peer endpoint TA. Uplink shadow endpoints" UpT and " The downstream shadow endpoint "DownT" and the legal interception endpoint Tm corresponding to the monitoring center (not shown) are bridged to a conference bridge where the conference context 3 is located. In this way, the upstream media stream and downstream media stream of the monitored user respectively pass the "upstream shadow endpoint" The IP streams of UpT and "Down Shadow Endpoint" DownT are mixed on the conference bridge, so that the monitoring function of endpoint TA is implemented.

The "uplink shadow endpoint" UpT and "downlink shadow endpoint" DownT and all auxiliary IP points on the conference bridge and the monitoring endpoint Tm are attached to the monitored endpoint TA and have a master-slave relationship with the monitored endpoint TA. This must be saved in the MGC Kind of relationship.

The above description is made by taking the calling user as the monitored object as an example. Those skilled in the art should understand that the called user can also be monitored as the monitoring object.

FIG. 4 is a flowchart of the media control corresponding to the monitoring of ordinary calls according to the present invention. The media control steps are:

1) Through the Megaco command Add, a monitoring endpoint Tm corresponding to the monitoring call media bearer is established in a new context ($).

2) Through the Megaco command Add, an auxiliary "upstream shadow endpoint" UpT is added to the context 1 corresponding to the monitored endpoint where the monitored user A is located, which is used to monitor the upstream media stream of the monitored user A. (By default, the endpoints in the newly added context are bidirectional topology connections with other endpoints.)

3) Via the Megaco command Add, add the auxiliary "downstream shadow endpoint" DownT to context 1 corresponding to the monitored endpoint where user A is located, which uses Come and listen to the downstream media stream of the monitored user A.

4) Establish a three-party conference bridge through the Megaco command Add, which includes endpoint T1 (first endpoint), endpoint T2 (second endpoint), and endpoint T3 (third endpoint). These endpoints provide endpoints for the conference bridge to provide services to the outside. .

5) The Megaco command Add adds an auxiliary IP point in the context where the endpoint Tm is located and assigns the remote IP as the endpoint T3.

6) Use the Megaco command Mod to configure the remote IPs of the shadow endpoints UpT and DownT as endpoints T1 and T2, respectively.

7) The Megaco command Mod is used to disconnect the possible two-way topological connection between the "uplink shadow endpoint" UpT and the opposite endpoint TA of the endpoint TA to avoid possible crosstalk.

8) Using the Megaco command Mod, disconnect the possible two-way topology connection between the "downlink shadow endpoint" DownT and the monitored user endpoint TA to avoid possible crosstalk.

Since the monitored user may perform various services, such as call forwarding, multi-call, MPTY, etc., the networking model must ensure that call monitoring does not fail due to the impact of these services. Under the networking model of the present invention using a softswitch system, this is not only ensured, but call monitoring is a limited set of media control processes for these services, with the set element being 2. In this way, the media control process of monitoring will not be increased due to the increase of services. This implementation method has good versatility and scalability.

Analyzing the network model shown in Figure 3, no matter what kind of service the user A does, there are only two possible results: the endpoint TA changes, and the endpoint TA changes. Therefore, we can define two media control processes for these two changes to realize the reconstruction of the listening connection network. Definition set ".

a = {C _{l 3} C ₂ }

Q: Endpoint TA changes, delete shadow endpoints UpT and DownT, and add endpoints UpT and DownT to the new endpoint TA context, change the conference bridge and The remote information of the corresponding IP point disconnects the topology connection between the endpoint TA and the endpoint DownT, disconnects the topology connection between the endpoint TA and the endpoint UpT.

C ₂ : End point TA, change, disconnect the topology connection between the new end point TA 'and the end point UpT.

Can analyze the general business: CH, CW, user 110, user A initiated MPT Y can be classified as media control process.

Call forwarding, user B's Call Retrieve, user B's HO, and user A's participation in MPTY can be classified as media control process C ₂ .

Therefore, the media control implementation method for solving call monitoring described in the present invention

1) The requirements of the legal monitoring function are met.

2) Adopting a softswitch architecture, call control is separated from media control, and the media control process added to implement the call monitoring service does not affect the original call signaling control, and does not change the original media connection of the original call. And media control processes.

3) The interface between the Media Control (MGC) and the Media Gateway (MGW) complies with the standard Megaco (h.248) protocol.

4) When the monitored user performs various business operations, the impact on this type of monitoring media control is limited, and a limited set of media control operations can be used to prevent the monitoring from being affected by the monitored user's business.

Therefore, as mentioned above, the call monitoring media control of the present invention is implemented in the following manner: A user initiates a call from one endpoint to another endpoint. After the call is successfully established, the originating or accepting endpoint is monitored, and the corresponding "uplink shadow endpoint" and "downlink shadow endpoint" are added to the context of the monitored endpoint. The "uplink shadow endpoint" and "downlink shadow endpoint" are IP endpoints with a media bearer attribute of SendOnly. The "uplink shadow endpoint" has only a two-way topology connection with the monitored endpoint; the "downlink shadow endpoint" only has the monitored endpoint. The peer endpoint has a bidirectional Topology connection. Bridge the "shadow endpoint" and the listening endpoint corresponding to the listening center to a conference bridge, respectively. In this way, the uplink media stream and downlink media stream of the monitored user are mixed on the conference bridge through the IP streams of the "upstream shadow endpoint" and the "downlink shadow endpoint" respectively, thereby achieving the function of endpoint monitoring.

"The shadow endpoint, and all auxiliary DP points on the conference bridge and the listening endpoint are attached to the monitored endpoint and have a master-slave relationship with the monitored endpoint. This relationship must be saved in the MGC.

The above-mentioned media control method for legal monitoring intercepts the copying of the media stream and networking occurs after both the calling party and the called party are successfully established.

In addition, the method includes the following processing principles:

When deleting the monitoring endpoint (such as stopping monitoring), you must delete all "shadow endpoints" and all auxiliary IP points on the conference bridge; when deleting the monitored endpoint (such as monitored user hanging up), you need to delete all "shadow endpoints" And the auxiliary IP points and monitoring endpoints on all conference bridges; when the monitored endpoint changes (such as a user making multiple calls or switching), reconstruct the "uplink shadow endpoint" and "downlink shadow endpoint" and change the IP points on the conference bridge. Remote attributes; For changes to the peer endpoint of the monitored endpoint (such as call forwarding by the peer user), it is necessary to disconnect the topology connection between the "uplink shadow endpoint" and the monitored peer endpoint.

The above description describes the lawful monitoring media control method of the present invention, but the scope of the present invention is not limited to the specific details and typical embodiments shown and described herein. Based on the above description and the drawings and claims, those skilled in the art should understand that various changes can be made thereto without departing from the spirit and scope of the invention as defined by the following claims and their equivalents. , Modifications and changes.

Claims

Rights request

1. A media control method for implementing legal interception, comprising the following steps:

2. The method according to claim 1, wherein: the uplink shadow endpoint and the downlink shadow endpoint are IP endpoints with an attribute of sendonly.

3. The method according to claim 1 or 2, wherein the uplink shadow endpoint is connected to the monitored endpoint topology, and the downlink shadow endpoint is connected to the peer endpoint topology of the monitored endpoint.

4. The method according to claim 1, wherein the copying and network monitoring of the media stream are performed after the calling party and the called party are successfully established.

5. The method according to claim 1, further comprising: disconnecting the topology connection between the monitored endpoint and the downstream shadow endpoint, and disconnecting the topology connection between the peer endpoint of the monitored endpoint and the upstream shadow endpoint.

6. The method according to claim 1, further comprising: when the monitored endpoint changes, reconstructing the uplink shadow endpoint and the downlink shadow endpoint at the new monitored endpoint.

7. The method according to claim 6, wherein the uplink is reestablished at the new monitored endpoint The shadow endpoint and the downlink shadow endpoint further include: changing remote information of an IP point corresponding to the shadow endpoint on the conference bridge.

8. The method according to claim 7, further comprising: after changing the remote information of the IP point corresponding to the shadow endpoint on the conference bridge, disconnecting the topology connection between the monitored endpoint and the downstream shadow endpoint, And disconnect the topological connection between the peer endpoint of the monitored endpoint and the upstream shadow endpoint.

9. The method according to claim 1, further comprising: disconnecting the topology connection between the uplink shadow endpoint and the peer endpoint of the monitored endpoint when the peer endpoint of the listening endpoint changes.

10. A media control method, comprising the following steps:

3) Through the Megaco command Add, add an auxiliary downlink shadow endpoint in the context corresponding to the monitored endpoint where the monitored object is located, which is used to listen to the downstream media stream of the monitored object;

5) Use the Megaco command Add to add a secondary IP point in the context of the listening endpoint and assign the remote IP as the third endpoint;

8) Disconnect the downstream shadow endpoint and the monitored endpoint through the Megaco command Mod Bidirectional topology connection.

11. The method according to claim 10, wherein: the uplink shadow endpoint and the downlink shadow endpoint are IP endpoints with an attribute of sendonly.

12. The method according to claim 10, further comprising: when the monitored endpoint changes, reconstructing the uplink shadow endpoint and the downlink shadow endpoint at the new monitored endpoint.

13. The method according to claim 12, wherein reconstructing the uplink shadow endpoint and the downlink shadow endpoint on the new monitored endpoint further comprises: changing remote information of the IP point corresponding to the shadow endpoint on the conference bridge.

14. The method according to claim 13, further comprising: after changing the remote information of the IP point corresponding to the shadow endpoint on the conference bridge, disconnecting the topology connection between the monitored endpoint and the downstream shadow endpoint, And disconnect the topology connection between the peer endpoint being monitored by the peer and the uplink shadow endpoint.

15. The method according to claim 10, further comprising: when the peer endpoint of the monitored endpoint changes, disconnecting the topology connection between the uplink shadow endpoint and the listening peer.