KR20070077716A - Interworking media gateway and metod of operating the gateway - Google Patents

Abstract

An interworking media gateway and an operation method of the interworking media gateway are provided to perform whether to fall back to a speech channel of a multimedia channel before starting an outbound call by controlling opening of a multimedia channel between a VoIP terminal and a mobile terminal only when the mobile terminal supports a 3G network and is located in an area of the 3G network. An IAM(Initial Address Message) is received from an MSC(Mobile Switching Center). Bearer capability information included in the IAM is read. When the IAM includes the first bearer capability information set in a multimedia mode, opening of a multimedia channel between an origination mobile terminal and a destination VoIP terminal is controlled. When the IAM does not include the first bearer capability information, opening of a speech channel between the origination mobile terminal and the destination VoIP terminal is controlled.

Description

Interworking media gateway and operation method of the interworking media gateway {INTERWORKING MEDIA GATEWAY AND METOD OF OPERATING THE GATEWAY}

1 is a diagram illustrating an entire network of a mobile communication network and a VoIP network including an IMG according to an embodiment of the present invention.

2 is a flowchart illustrating a method of operating an IMG according to a first embodiment of the present invention.

3 is a flowchart illustrating a method of operating an IMG according to embodiment 2-1 of the present invention.

4 is a flowchart illustrating a method of operating an IMG according to embodiment 2-2 of the present invention.

5 is a flowchart illustrating a method of operating an IMG according to embodiment 2-3 of the present invention.

6 is a flowchart illustrating a method of operating an IMG according to a third embodiment of the present invention.

7 is a block diagram showing the configuration of an IMG according to the present invention;

8 is a block diagram showing the configuration of a call signal matching section of the IMG according to the present invention;

9 is a block diagram showing the configuration of a service control matching unit of the IMG according to the present invention;

10 is a block diagram showing the configuration of a basic call control unit of an IMG according to the present invention;

11 is a block diagram showing a configuration of a multimedia control unit of the IMG according to the present invention.

<Explanation of symbols for the main parts of the drawings>

210: the IMG receives a request for a multimedia call connection to the incoming VoIP terminal from the originating mobile communication terminal

220: speech channel setting step between IMG originating mobile communication terminal and incoming VoIP terminal

230: IMG multimedia channel setting step between the outgoing mobile terminal and the incoming VoIP terminal

The present invention relates to an interworking media gateway (IMG) for controlling fallback of a multimedia mode and a speech mode between a mobile communication network and a VoIP network, and an operation method of the interworking media gateway. Specifically, in the call setup between the mobile communication terminal and the VoIP terminal, when the mobile communication terminal is a mobile communication terminal (first condition) supporting 3G network and is located in the 3G network area (second condition), the mobile Controls the opening of the multimedia channel between the communication terminal and the VoIP terminal, and controls the opening of the speech channel between the mobile communication terminal and the VoIP terminal when the mobile communication terminal does not satisfy the first condition and the second condition at the same time. A method for operating a working media gateway and the interworking media gateway The.

Recently, as communication networks continue to evolve, there is a growing interest in next generation communication networks (NGNs) or broadband convergence networks that replace legacy communication networks such as PSTN. The next generation network or broadband communication network integrates all communication networks such as general telephone network (PSTN), asynchronous transmission (ATM) network, frame relay (FR) network, private network, and wireless communication network into a packet-based common network. It is known as a voice-video-data integrated network to provide a flexible and open network solution and a variety of applications, as well as reducing deployment and operating costs.

As the network evolves and the demand for the user's communication service continues to increase, various multimedia communication services that cannot be provided in the conventional legacy communication network will be provided in the next generation communication network. The most important configuration for providing multimedia communication services in this next generation communication network is IMG (Interworking Media Gateway).

IMG is SSW, GK, CA (Call Agent), MGC (Media GW Controller), MSC, WCDMA- such as wired network, wireless network, 3GPP network, VoIP network (H.323 communication network, SIP network, MGCP network, MEGACO network). It is a device that provides signal, multimedia stream transmission matching and multimedia source coding matching for video, audio, or data (hereinafter, referred to as multimedia data) suitable for each communication network through signal matching from an MSC (or 3G-MSC), an MSC server, or the like. IMG supports SIP / H.323 protocol conversion, H.324M protocol conversion, Media Stream Translation, H.245 signaling conversion, Media transport signaling conversion, SIP / H323 End It performs the functions of Point and H.324M terminal emulation.

As such, the IMG may control call setup between the mobile communication network and the VoIP network. The call may be implemented as a multimedia call such as a video call. Of course, video telephony via VoIP is currently in service, but video telephony via mobile communication networks is available only in 3G mobile communication terminals supporting 3G networks. However, the penetration rate of the 3G mobile communication terminal is still low.

Accordingly, the IMG is more likely to receive a call connection between the 2G mobile terminal and the VoIP terminal than when a call connection is requested between the 3G mobile terminal and the VoIP terminal. However, since most IMGs are implemented and released for the 3G network only, since two tasks cannot be simultaneously performed in the same channel even when a request for a call connection to the 2G mobile communication terminal is requested, the call connection of the 2G mobile communication terminal can be performed. I can't control it.

According to the problems of the prior art, it is required to develop an IMG that can determine whether the mobile communication terminal is a terminal supporting 3G network and control the fallback of the opening of the multimedia channel or the opening of the speech channel accordingly. have.

The present invention has been made to improve the prior art as described above, by reading the bearer capability information contained in the ISDN User Part (ISP) IAM message received from the mobile communication terminal, the bearer capability information is multimedia It is an object of the present invention to provide an operating method of IMG and IMG capable of supporting a fallback between 3G and 2G networks only by ISUP signaling by controlling the opening of the multimedia channel between the mobile communication terminal and the VoIP terminal only when set to the mode. do.

In addition, the present invention, when receiving a request for opening a multimedia channel for a predetermined mobile communication terminal from the VoIP terminal, and transmits a query (Query) for the terminal information and location information of the mobile communication terminal to the HLR (Home Location Register) And receiving a response message corresponding to the query from the HLR, so that the mobile communication terminal is a mobile communication terminal supporting a 3G network and is located in the 3G network area only when the multimedia channel is between the VoIP terminal and the mobile communication terminal. It is an object of the present invention to provide an operating method of IMG and IMG capable of performing whether to fall back to the speech channel of the multimedia channel before the start of an outbound call.

In addition, when the multimedia channel for a predetermined mobile communication terminal is requested from a VoIP terminal, the present invention first opens the multimedia channel and then, when a synchronization flag is detected from the mobile communication terminal, the multimedia channel. It is an object of the present invention to provide an operating method of IMG and IMG which can control the fallback while maintaining the existing signaling by maintaining a channel and controlling the fallback to the speech channel of the multimedia channel when the synchronization flag is not detected. do.

In addition, the present invention, after the multimedia channel is opened between the 3G mobile communication terminal and the VoIP terminal, when the 3G mobile communication terminal moves out of the 3G network area, by analyzing the PCM according to the synchronization flag of the 3G mobile communication terminal and the 3G After recognizing that the mobile communication terminal operates in the speech mode, the multimedia channel falls back to the speech channel, thereby operating a method of operating IMG and IMG that can control a call connection by distinguishing between 3G and 2G networks in the same channel. It aims to provide.

In order to achieve the above object and solve the problems of the prior art, the operation method of the interworking media gateway according to the present invention, the initial address message (IAM: Initial Address Message) (IAM) from a predetermined mobile switching center (MSC) Receiving the initial address message corresponding to a call setup message (SETUP) sent by a given originating mobile communication terminal to the mobile exchange for a predetermined incoming VoIP terminal; Reading bearer capability information included in the initial address message; Controlling opening of a multimedia channel between the originating mobile communication terminal and the terminating VoIP terminal when the initial address message includes first bearer performance information set to a multimedia mode as a result of the reading; And controlling the opening of a speech channel between the originating mobile communication terminal and the destination VoIP terminal when the initial address message does not include the first bearer capability information.

In addition, the operating method of the interworking media gateway according to the present invention comprises the steps of: receiving an INVITE message for a predetermined incoming mobile communication terminal from a predetermined originating VoIP terminal, wherein the invite message is used to receive multimedia channel open information. Including-; Transmitting an initial address message (IAM) corresponding to the invite message to a predetermined mobile switching center (MSC)-the mobile exchange corresponding to the initial address message to the destination mobile communication terminal; Send a call setup message (SETUP); Receiving a predetermined address complete message (ACM) from the mobile switch, the address complete message corresponding to an alerting of the called mobile communication terminal according to the call setup message; Reading an optional field of the address completion message; Controlling opening of a multimedia channel between the originating VoIP terminal and the called mobile communication terminal when the first bearer performance information set to the multimedia mode is included in the additional field of the address completion message as a result of the reading; And controlling opening of a speech channel between the originating VoIP terminal and the called mobile terminal when the first bearer performance information is not included in the additional field of the address completion message. .

In addition, the operating method of the interworking media gateway according to the present invention comprises the steps of: receiving an INVITE message for a predetermined incoming mobile communication terminal from a predetermined originating VoIP terminal, wherein the invite message is used to receive multimedia channel open information. Includes-; Transmitting a query for information and location of the called mobile communication terminal to a predetermined home location register (HLR); Receiving predetermined response information from the home location register; Reading the response information; Controlling the opening of a multimedia channel between the calling VoIP terminal and the called mobile terminal when the called mobile terminal satisfies a first condition and a second condition at the same time. A condition in which a mobile communication terminal is a terminal capable of opening the multimedia channel, and the second condition is a condition in which the called mobile communication terminal is located in an area in which the multimedia channel can be opened; And controlling the opening of a speech channel between the calling VoIP terminal and the called mobile terminal when the called mobile terminal does not satisfy the first condition and the second condition at the same time. Include.

In addition, the operating method of the interworking media gateway according to the present invention comprises the steps of: receiving an INVITE message for a predetermined incoming mobile communication terminal from a predetermined originating VoIP terminal, wherein the invite message is used to receive multimedia channel open information. Includes-; Controlling opening of a multimedia channel between the calling VoIP terminal and the called mobile terminal; Transmitting a synchronization flag corresponding to the multimedia channel to the called mobile communication terminal; Maintaining the open of the multimedia channel when receiving a flag corresponding to the synchronization flag transmission from the called mobile communication terminal; And if a flag corresponding to the synchronization flag transmission is not received from the called mobile communication terminal, controlling a fallback of the multimedia channel to a speech channel.

In addition, the operating method of the interworking media gateway according to the present invention comprises the steps of: receiving an initial address message (IAM) from a predetermined mobile switching center (MSC)-the initial address message is a predetermined origination Corresponds to a call setup message (SETUP) sent by the mobile communication terminal to the mobile switch for a predetermined incoming VoIP terminal; Reads bearer capability information included in the initial address message, and when the initial address message includes first bearer capability information set as a multimedia channel, a multimedia channel between the originating mobile communication terminal and the terminating VoIP terminal. Controlling the opening of the; Analyzing PCM data corresponding to the originating mobile communication terminal when the multimedia channel is maintained; And controlling a fallback of the multimedia channel to a speech channel when it is determined that the originating mobile communication terminal has moved to an area in which the multimedia channel cannot be opened. do.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a diagram illustrating an entire network of a mobile communication network and a VoIP network including an IMG according to an embodiment of the present invention.

In an embodiment of the present invention, an interworking media gateway (hereinafter, IMG) performs a media channel fallback between a mobile communication network and a VoIP network. That is, when the mobile communication terminal requests a call connection to the VoIP terminal, the call may be performed fallback, and the callback may be performed even when the VoIP terminal requests the call connection to the mobile communication terminal.

The fallback may be performed between a multimedia channel and a speech channel in response to the call. That is, the fallback may be performed depending on whether the call is a call requiring opening of a multimedia channel such as a video call or a call requiring only opening of a speech channel, such as a general voice call.

The fallback may be performed depending on whether the mobile communication terminal is a 3G terminal or a 2G terminal. When the mobile communication terminal is a 3G terminal, the IMG can provide a video telephone service by controlling the opening of a multimedia channel through a 3G network between the 3G terminal and the VoIP terminal. However, when the mobile communication terminal is a 2G terminal, the IMG cannot control the opening of the multimedia channel and thus cannot provide the video telephone service. Therefore, in this case, the IMG may control the opening of a speech channel through a 2G network between the 2G terminal and the VoIP terminal.

As shown in FIG. 1, the IMG may be connected to a SIP / H323 terminal through a SIP / H323 protocol of a soft switch (SSW), and may transmit and receive media with the SIP / H323 terminal through an RTP protocol. In addition, the IMG can access the 2G mobile communication terminal through the 2G network by connecting to the BSC / MSC of the 2G network through the SS7 network (E1 Audio). In addition, the IMG can access the 3G mobile communication terminal through the 3G network by connecting to the BSC / MSC of the 3G network through the SS7 network (E1 Audio / Video).

The IMG operation method of the present invention performed according to the network configuration can be divided into five embodiments as follows.

1) In the first mobile terminal and the incoming VoIP terminal, the first embodiment reads bearer capability information included in the ISUP message of the calling mobile terminal and falls back the media channel.

2) In the case of an outgoing VoIP terminal and a terminating mobile communication terminal, a method of falling back a media channel by reading bearer capability information included in an ISUP message of the terminating mobile communication terminal is performed.

3) In the case of the outgoing VoIP terminal and the terminating mobile communication terminal, the method returns the media channel by inquiring the information of the terminating mobile communication terminal to the home location register (HLR) in the second embodiment.

4) In the case of the outgoing VoIP terminal and the terminating mobile communication terminal, the PCM data of the terminating mobile communication terminal is analyzed to fall back the media channel.

5) When the 3G mobile communication terminal moves from the 3G network to the 2G network after the multimedia channels of the 3G mobile communication terminal and the VoIP terminal are opened, a method of analyzing the PCM data of the 3G mobile communication terminal and falling back the media channel 3 Examples.

As described above, the operation method of the IMG according to the present invention may be divided into embodiments. The VoIP terminal may be a terminal supporting the H323 protocol or a terminal supporting the SIP protocol. The mobile communication terminal may be a 3G terminal or a 2G terminal. However, in the third embodiment, the mobile communication terminal may be implemented as a mobile communication terminal supporting both 3G and 2G.

In addition, the multimedia channel between the mobile communication terminal and the VoIP terminal may be configured to include all protocols used in a general 3G network. However, in the present specification, for convenience of description, the multimedia channel between the mobile communication terminal and the VoIP terminal will be described with an example of setting according to the H223 protocol. Hereinafter, an IMG operating method of the present invention will be described with reference to each drawing.

2 is a flowchart illustrating a method of operating an IMG according to a first embodiment of the present invention.

In the first embodiment of the present invention, the mobile communication terminal may be implemented as the calling terminal, and the VoIP terminal may be implemented as the called terminal. The mobile communication terminal may be a 3G terminal or a 2G terminal. The mobile exchange may be implemented with Mobile Switching Center Originating (MSC) or Base Station Controller (BSC). The incoming VoIP terminal may be implemented as a SIP / H323 terminal.

In step 210, the outgoing mobile communication terminal transmits a call setup message (SETUP) to the mobile exchange for connection with the incoming VoIP terminal. The mobile exchange requests the call connection by transmitting an initial address message (IAM) corresponding to the call setup message to the IMG. The initial address message is a kind of ISUP message and includes a number and various information necessary for call processing and routing. As part of the information, the IAM includes bearer capability information indicating the type of call that the originating mobile communication terminal wants to request.

The bearer performance information may be set in a multimedia mode or may be set in a speech mode. That is, when the originating mobile communication terminal is a 3G terminal, the bearer performance information may be set in a multimedia mode. When the originating mobile communication terminal is a 2G terminal, the bearer performance information may be set to a speech mode.

Accordingly, the IMG reads bearer performance information of the IAM received from the mobile exchange. As a result of the reading, if the bearer capability information of the IAM is not the first bearer capability information set in the multimedia mode, the IMG falls back the call of the originating mobile communication terminal to the speech mode. That is, since the IMG is initially set to a 3G network, the IMG falls back to the speech mode and controls opening of a speech channel between the originating mobile communication terminal and the terminating VoIP terminal.

In step 220, the IMG sends an INVITE message to the called VoIP terminal and receives a 100 TRYING message from the called VoIP terminal. The IMG sends an address complete message (ACM) to the mobile exchange, and the mobile exchange sends an ALERTING message to the originating mobile terminal. In addition, when the called VoIP terminal transmits a 200 OK message, the IMG sends an answer message (ANM) to the mobile exchange, and the mobile exchange performs a call connection corresponding to the ANM. A speech channel is opened between the calling mobile terminal and the called VoIP terminal.

However, in step 210, when the bearer performance information of the IAM is read and the bearer performance information of the IAM includes the first bearer performance information set in the multimedia mode, the IMG operates in the multimedia mode. That is, the IMG may recognize that the originating mobile communication terminal is a 3G terminal and perform a series of operations according to a 3G network.

In step 230, the IMG sends an INVITE message to the called VoIP terminal and receives a 100 TRYING message from the called VoIP terminal. The IMG sends an ACM to the mobile exchange, and the mobile exchange sends an ALERTING message to the originating mobile communication terminal. In addition, when the terminating VoIP terminal transmits a 200 OK message, the IMG transmits an ANM to the mobile exchange, and the mobile exchange controls the call connection between the originating mobile communication terminal and the terminating VoIP terminal.

Thereafter, the IMG performs H223 level setting with the originating mobile communication terminal and the terminating VoIP terminal. In each of the H223 level settings, the IMG generates a synchronization flag for each level of H223, which is composed of four levels of 0 levels, 1 level, 2 levels, and 3 levels. Send continuously to the terminal. The IMG completes the H223 level setting when at least 16 flags received from the originating mobile communication terminal and the transmitted flags are the same. Thus, the multimedia channel between the originating mobile communication terminal and the called VoIP terminal can be opened.

3 is a flowchart illustrating a method of operating an IMG according to embodiment 2-1 of the present invention.

In Embodiment 2-1 of the present invention, the VoIP terminal may be implemented as the calling terminal, and the mobile communication terminal may be implemented as the called terminal. The mobile communication terminal may be a 3G terminal or a 2G terminal. The mobile exchange may be implemented with Mobile Switching Center Originating (MSC) or Base Station Controller (BSC). The incoming VoIP terminal may be implemented as a SIP / H323 terminal.

In step 310, when the originating VoIP terminal sends an INVITE message for setting up a multimedia channel with an incoming mobile terminal to the IMG, the IMG sends an IAM to the mobile exchange. The IAM may include bearer capability information for inquiring whether the terminating mobile communication terminal is a 2G terminal or a 3G terminal.

The mobile exchange transmits a SETUP message to the called mobile communication terminal after receiving the IAM. In response to receiving the SETUP message, the terminating mobile communication terminal sends an ALERTING message to the mobile exchange, and the mobile exchange sends an ACM to the IMG.

The mobile exchange records bearer performance information in an optional field of the ACM and transmits it to the IMG. That is, when the incoming mobile communication terminal is a terminal capable of opening the multimedia channel (3G terminal) and is located in an area (3G network area) where the multimedia channel can be opened, the multimedia mode is set in an additional field of the ACM. The first bearer performance information may be recorded. However, when the terminating mobile communication terminal does not satisfy all of the above conditions, the mobile exchange may record bearer performance information in which a speech mode is set without recording the first bearer performance information in an additional field of the ACM. .

Accordingly, the IMG transmits a 100 TRYING message to the originating VoIP terminal, and then reads bearer performance information recorded in the supplementary fill of the ACM received from the mobile exchange. As a result of the reading, if the first bearer performance information is not included in the additional field of the ACM, the IMG falls back to the call mode of the originating VoIP terminal in the speech mode. That is, since the IMG is initially set to a 3G network, the IMG falls back to the speech mode to control the opening of a speech channel between the calling VoIP terminal and the called mobile communication terminal.

In step 320, when the terminating mobile communication terminal sends a CONNECT message to the mobile exchange, the mobile exchange sends an ANM message to the IMG. In response to receiving the ANM message, the IMG transmits a 200 OK message to the originating VoIP terminal, thereby opening a speech channel between the originating VoIP terminal and the called mobile communication terminal.

However, as a result of reading the bearer performance information recorded in the additional field of the ACM in step 310, if the first bearer performance information is included in the additional field of the ACM, the IMG operates in the multimedia mode. That is, the IMG may recognize that the called mobile communication terminal is a 3G terminal and perform a series of operations according to a 3G network.

In step 330, when the terminating mobile communication terminal sends a CONNECT message to the mobile exchange, the mobile exchange sends an ANM message to the IMG. Upon receipt of the ANM message, the IMG sends a 200 OK message to the originating VoIP terminal.

Thereafter, the IMG performs H223 level setting with the originating VoIP terminal and the terminating mobile communication terminal. In each of the H223 level settings, the IMG sets a synchronization flag to be used for each level of H223, which is composed of a total of four levels of 0, 1, 2, and 3 levels. Send continuously to the terminal. The IMG completes the H223 level setting when at least 16 flags received from the destination mobile communication terminal and the transmitted flags are the same. Thus, the multimedia channel between the calling VoIP terminal and the called mobile terminal can be opened.

4 is a flowchart illustrating a method of operating an IMG according to embodiment 2-2 of the present invention.

In embodiment 2-2 of the present invention, the VoIP terminal may be implemented as the calling terminal, and the mobile communication terminal may be implemented as the called terminal. The mobile communication terminal may be a 3G terminal or a 2G terminal. The mobile exchange may be implemented with Mobile Switching Center Originating (MSC) or Base Station Controller (BSC). The incoming VoIP terminal may be implemented as a SIP / H323 terminal. In addition, the IMG operating method according to embodiment 2-2 of the present invention may be implemented including a home location register (HLR).

In step 410, when the originating VoIP terminal transmits an INVITE message for setting up a multimedia channel with the terminating mobile terminal to the IMG, the IMG queries the terminal information and the location information for the terminating mobile terminal with the HLR. QUERY). If the HLR sends a response message (RESPONSE) containing the destination mobile communication terminal information and the location information of the destination mobile communication terminal to the IMG, the IMG reads the response message.

As a result of the reading, the first condition that the terminating mobile communication terminal is a terminal (3G terminal) capable of setting the multimedia channel, and the terminating mobile station is located in an area (3G network area) where the multimedia channel can be set If the two conditions are not met simultaneously, the IMG falls back to the speech mode of the originating VoIP terminal. That is, since the IMG is initially set to a 3G network, the IMG falls back to the speech mode to control the opening of a speech channel between the calling VoIP terminal and the called mobile communication terminal.

In step 420, the IMG sends an IAM to the mobile exchange. The IAM may include bearer performance information set to speech mode. The mobile exchange receiving the IAM transmits a SETUP message to the called mobile communication terminal. The terminating mobile communication terminal sends an ALERTING message to the mobile exchange, and the mobile exchange sends an ACM to the IMG. In addition, when the terminating mobile communication terminal transmits a CONNECT message to the mobile exchange, the mobile exchange transmits an ANM to the IMG, so that a speech channel between the originating VoIP terminal and the terminating mobile communication terminal can be opened.

However, in step 410, if the incoming mobile communication terminal satisfies both the first condition and the second condition as a result of reading the response message, the IMG operates in the multimedia mode. That is, the IMG may recognize that the called mobile communication terminal is a 3G terminal and perform a series of operations according to a 3G network.

In step 430, the IMG sends an IAM to the mobile exchange. The IAM may include bearer performance information set to speech mode. The mobile exchange receiving the IAM transmits a SETUP message to the called mobile communication terminal. The terminating mobile communication terminal sends an ALERTING message to the mobile exchange, and the mobile exchange sends an ACM to the IMG. In addition, when the terminating mobile communication terminal transmits a CONNECT message to the mobile exchange, the mobile exchange transmits an ANM to the IMG.

Thereafter, the IMG performs H223 level setting with the originating VoIP terminal and the terminating mobile communication terminal. In each of the H223 level settings, the IMG sets a synchronization flag to be used for each level of H223, which is composed of four levels of 0 levels, 1 level, 2 levels, and 3 levels. And continuously transmit to the called mobile communication terminal. The IMG completes the H223 level setting when at least 16 flags received from the destination mobile communication terminal and the transmitted flags are the same. Thus, the multimedia channel between the incoming mobile communication terminal can be opened.

5 is a flowchart illustrating a method of operating an IMG according to embodiment 2-3 of the present invention.

In embodiment 2-2 of the present invention, the VoIP terminal may be implemented as the calling terminal, and the mobile communication terminal may be implemented as the called terminal. The mobile communication terminal may be a 3G terminal or a 2G terminal. The mobile exchange may be implemented with Mobile Switching Center Originating (MSC) or Base Station Controller (BSC). The incoming VoIP terminal may be implemented as a SIP / H323 terminal.

In step 510, when the originating VoIP terminal sends an INVITE message for setting up a multimedia channel with an incoming mobile terminal to the IMG, the IMG sends an IAM to the mobile exchange. The mobile exchange transmits a SETUP message to the called mobile communication terminal after receiving the IAM. In response to receiving the SETUP message, the terminating mobile communication terminal sends an ALERTING message to the mobile exchange, and the mobile exchange sends an ACM to the IMG. The IMG sends a 100 TRYING message to the originating VoIP terminal.

Thereafter, when the terminating mobile communication terminal sends a CONNECT message to the mobile exchange, the mobile exchange transmits an ANM message to the IMG. Upon receipt of the ANM message, the IMG transmits a 200 OK message to the calling VoIP terminal, thereby opening a multimedia channel between the calling VoIP terminal and the called mobile terminal. That is, in the embodiment 2-3 of the present invention, the IMG first opens a multimedia channel between the calling VoIP terminal and the called mobile terminal, and then reads whether the called mobile terminal is a 3G terminal or a 2G terminal. .

In step 520, after opening the multimedia channel, the IMG performs H223 level setting with the calling VoIP terminal and the called mobile terminal. In the H223 level setting with the terminating mobile communication terminal, a synchronization flag used for each level of the H223 is continuously transmitted to the terminating mobile communication terminal.

However, if the same flag as the transmitted flag is not received from the terminating mobile communication terminal, the IMG falls back to the speech mode of the originating VoIP terminal. That is, the IMG determines that the called mobile communication terminal is a 2G terminal instead of the 3G terminal, and falls back the call in the speech mode to control the opening of a speech channel between the calling VoIP terminal and the called mobile communication terminal.

In operation 520, when the same flag as the transmitted flag is received from the called mobile communication terminal, the IMG operates in a multimedia mode. That is, the terminating mobile communication terminal determines that the multimedia mode is a 3G terminal and maintains the opening of the multimedia channel between the calling VoIP terminal and the terminating mobile communication terminal.

Thereafter, the IMG performs H223 level setting with the originating VoIP terminal and the terminating mobile communication terminal. In each of the H223 level settings, the IMG transfers a synchronization flag to be used for each level of the H223, which is composed of four levels of 0 levels, 1 level, 2 levels, and 3 levels. Continuous transmission to the communication terminal. The IMG completes the H223 level setting when at least 16 flags received from the destination mobile communication terminal and the transmitted flags are the same. As a result, the multimedia channel open between the calling VoIP terminal and the called mobile terminal can be maintained.

6 is a flowchart illustrating a method of operating an IMG according to a third embodiment of the present invention.

In the third embodiment of the present invention, the mobile communication terminal may be implemented as the calling terminal, and the VoIP terminal may be implemented as the called terminal. The mobile communication terminal is a 3G terminal and may also support a call connection according to a 2G network. That is, the outgoing mobile communication terminal can operate in both 3G and 2G networks. When the originating mobile communication terminal moves from the 3G network to the 2G network, the originating mobile communication terminal may operate to be handed off to the 2G mobile communication network. The mobile exchange may be implemented with Mobile Switching Center Originating (MSC) or Base Station Controller (BSC). The incoming VoIP terminal may be implemented as a SIP / H323 terminal.

In step 610, the outgoing mobile terminal transmits a SETUP message to the mobile exchange for a call connection with the incoming VoIP terminal. The mobile exchange sends the IAM corresponding to the SETUP message to the IMG to request the call connection. The IAM includes first bearer capability information set in a multimedia mode, meaning information indicating that the originating mobile communication terminal is a 3G terminal.

The IMG operates in the multimedia mode after checking the first bearer performance information from the IAM. The IMG sends an INVITE message to the terminating VoIP terminal and receives a 100 TRYING message from the terminating VoIP terminal. The IMG sends an ACM to the mobile exchange, and the mobile exchange sends an ALERTING message to the originating mobile communication terminal. In addition, when the called VoIP terminal transmits a 200 OK message, the IMG transmits an ANM to the mobile exchange, and the mobile exchange transmits a CONNECT message to the originating mobile communication terminal, whereby the called mobile communication terminal and the incoming call are received. The multimedia channel between the VoIP terminals is opened.

However, in step 620, when the outgoing mobile communication terminal moves from the 3G network to the 2G network, the outgoing mobile communication terminal is handed off to the 2G network to operate in speech mode. Therefore, the multimedia channel call connection between the calling mobile terminal and the called VoIP terminal cannot be maintained.

In step 630, the IMG may detect the movement of the outgoing mobile terminal to the 2G network by analyzing the PCM data corresponding to the outgoing mobile communication terminal. That is, the IMG determines that the outgoing mobile communication terminal moves to a 2G network in which the multimedia channel cannot be opened when the synchronization flag corresponding to the outgoing mobile communication terminal according to the maintenance of the multimedia channel is no longer detected. can do.

Accordingly, the IMG controls a fallback of the multimedia channel between the originating mobile communication terminal and the called VoIP terminal to the speech channel. Therefore, the outgoing mobile communication terminal and the incoming VoIP terminal can maintain a call connection through the speech mode.

So far, the operation method of the IMG according to each embodiment has been described. The IMG operation method according to each embodiment can be summarized as follows.

1) Embodiment 1 and Embodiment 2-1

The IMG reads bearer capability information included in an ISDN (IDN) User Part (ISP) IAM message received from the mobile communication terminal, and multimedia between the mobile communication terminal and the VoIP terminal only when the bearer capability information is set to the multimedia mode. By controlling the opening of the channel, it is possible to support fallback between 3G and 2G networks using only ISUP signaling.

2) Example 2-2

When the IMG receives a request for opening a multimedia channel for a predetermined mobile communication terminal from a VoIP terminal, a query for terminal information and location information of the mobile communication terminal is transmitted to a home location register (HLR), and the HLR A response message corresponding to the query is received from the mobile terminal, and the multimedia channel is opened between the VoIP terminal and the mobile communication terminal only when the mobile communication terminal is a mobile communication terminal supporting a 3G network and located in the 3G network area. By controlling, it is possible to perform whether to fall back to the speech channel of the multimedia channel before the start of an outbound call.

3) Example 2-3

When the IMG receives a request for opening a multimedia channel for a predetermined mobile communication terminal from a VoIP terminal, the multimedia channel is opened first, and when the synchronization flag is detected from the mobile communication terminal, the multimedia channel is maintained. If the synchronization flag is not detected, the fallback can be controlled while maintaining the existing signaling by controlling the fallback of the multimedia channel to the speech channel.

4) Third embodiment

When the 3G mobile communication terminal moves out of the 3G network area after IMG opens a multimedia channel between the 3G mobile communication terminal and the VoIP terminal, the 3G mobile communication terminal is analyzed by analyzing the PCM according to the synchronization flag of the 3G mobile communication terminal. After recognizing that the device operates in the speech mode, the multimedia channel falls back to the speech channel, so that the call connection can be controlled by dividing the 3G network and the 2G network in the same channel.

Hereinafter, a configuration of an IMG for performing an operation according to each embodiment will be described with reference to FIGS. 7 to 11.

7 is a block diagram showing the configuration of an IMG according to the present invention.

The IMG according to the present invention includes a service control matching unit (SCIP), a call signal matching unit (CSIP), an operation management unit (OAMP), a service control application unit (SCAP), a basic call control unit (BCCP), and a multimedia control unit. . The multimedia controller includes a multimedia transmission controller (MTCP), a multimedia resource controller (MRCP), a multimedia file storage device, and a multimedia resource processor (MRPP).

The basic call control unit receives a call setup request transmitted from a mobile terminal from a mobile switching center (MSC) and requests a call connection to a called terminal through the MSC. The call establishment request includes caller or called party subscriber profile information regarding the multimedia ringback tone service.

The call signal matching unit performs an H.223 level setting and an H.245 negotiation procedure with the calling terminal and the called terminal through the basic call controller.

The multimedia controller reproduces and transmits predetermined multimedia data set by the caller or the called party to the calling terminal by referring to a predetermined subscriber database, and responds to the hook off response of the called terminal. Stops playing.

The characteristics and functions of each device included in the IMG illustrated in FIG. 7 will be described in detail with reference to FIGS. 8 to 11.

8 is a block diagram showing the configuration of a call signal matching unit of the IMG according to the present invention.

Call Signaling Interface Part (CSIP, Call Signaling Interface Part) of IMG according to the present invention is H323 matching module, SIP matching module, MGCP matching module, H248 / MEGACO matching module, R1 matching module, R2 matching module, PRI matching module, 3G -ISUP matching module, ISUP matching module, SIGTRAN matching module, SS7 MTP1, 2, 3 matching module.

The call signal matching unit provides a call signal matching function necessary for interworking with another network.

The H323 signal matching module uses the ITU_T H.323 standard for H.323 messages received via TCP / IP from SSW, GK, and T-MG to interoperate with GK (Gate Keeper) and T-MG (Trunk Media Gateway). It provides a function to decode according to the H.323 message, and encodes an H.323 message according to the ITU_T H.323 standard and transmits it to GK, T-MG, etc. In addition, it performs call connection management and control functions for call signaling with GK and T-MG.

SIP signal matching module provides the function to decode SIP message received from GK and T-MG via TCP / IP or UDP / IP according to IETF SIP standard for interworking with SSW, T-MG, etc. Is encoded according to IETF SIP standard and transmitted to SSW, T-MG, etc. It also performs call connection management and control for call signaling with SSW, T-MG, and so on.

MGCP Signal Matching Module provides the function to decode MGCP messages received through TCP / IP or UDP / IP from SSW, MGC, CA (Call Agent) according to IETF MGCP specification for interworking with SSW, MGC, CA, etc. In addition, the MGCP message is encoded according to the IETF MGCP standard and transmitted to the SSW (Soft Switch), MGC (Media Gateway Controller), CA (Call Agent) and the like. In addition, it performs call connection management and control functions for call signaling with SSW, MGC, CA, and the like.

The MEGACO Signal Matching Module decodes MEGACO messages received via TCP / IP or UDP / IP from SSW, MGC, CA according to the IETF MEGACO and ITU-T H.248 specifications for interworking with SSWMGC, CA, etc. It also provides the function to encode MEGACO messages according to IETF MEGACO and ITU-T H.248 standards and send them to SSW, MGC, CA, etc. In addition, it performs call connection management and control functions for call signaling with SSW, MGC, CA and the like.

The R2 signal matching module provides a function of decoding the R2 signaling message received through the E1 or T1 link from the exchange according to the ITU-T R2 specification in order to interwork with the existing PSTN exchange, and the R2 signaling message to the ITU-T R2. It provides the function of encoding according to the standard and transmitting it to the exchange side. In addition, it performs call connection management and control functions for call signaling with the exchange.

The PRI signal matching module provides the function to decode PRI signaling messages received through the E1 or T1 link from the exchange according to the ITU-T PRI specification in order to interoperate with existing PSTN or ISDN exchanges. It provides the function of encoding according to T PRI standard and transmitting to exchange. In addition, it performs call connection management and control functions for call signaling with the exchange.

The ISUP signal matching module provides the function of decoding the ISUP signaling message received through the E1 or T1 link from the exchange according to the ITU-T ISUP standard in order to interoperate with an existing PSTN or ISDN exchange. It provides the function of encoding according to T ISUP standard and transmitting to exchange. In addition, it performs call connection management and control functions for call signaling with the exchange.

The SS7 matching module is a base protocol interface for transmitting and receiving ISUP signaling messages and provides MTP1, MTP2, and MTP3 protocol functions.

SIGTRAN signal matching module provides the function to decode SIGTRAN signaling message received from SG through TCP / IP or UDP / IP or SCTCP / IP according to IETF SIGTRAN standard to interwork with SG, and IETF to decode ISUP signaling message. Provides the function of encoding according to SIGTRAN standard and transmitting to SG side. It also performs call connection management and control for call signaling with the SG.

The 3G-ISUP signal matching module provides a function of decoding a 3G-ISUP signaling message received from the MSC via an E1 or T1 link according to the 3GPP ISUP standard in order to interwork with the 3GPP MSC, and decodes the 3G-ISUP signaling message to the 3GPP ISUP. It provides the function of encoding according to the standard and transmitting it to the exchange side. In addition, it performs call connection management and control functions for call signaling with the exchange.

9 is a block diagram showing the configuration of the service control matching unit of the IMG according to the present invention.

The service control interface part (SCIP) of the IMG according to the present invention includes a CAP matching module, a MAP matching module, a WIN / WIN + (Wireless Intelligent Network) matching module, an INAP (Intelligent Network Application Protocol) matching module, and a SIP. (Session Initiation Protocol) matching module, VXML (Voice XML) matching module, PARLAY matching module, JAIN (JAVA Advanced Intelligent Network) matching module, AU matching module, call control XML (ccXML) matching module, SS7 Transaction Capability Application Part ) / MTP1,2,3 (Message Transfer Part 1,2,3) matching module.

The service control matching unit provides a service control interworking function with equipment (eg, SCP, AS (Application Server), etc.) that performs service logic to provide multimedia services such as various voices or videos in a communication network. Accordingly, the IMG receives the service control message of the service control device and records, transmits, media mixed, DTMF collection, automatic speech recognition (ASR) and speech synthesis (TTS: Text-To-) of various multimedia according to the message content. Speech).

WIN matching module provides the function to decode WIN / WIN + signaling message received from SCP through SS7 network according to national / international standard for interworking with service control device (SCP) and decode WIN / WIN + signaling message to domestic / international standard. Provides the function of encoding according to international standard and transmitting to SCP. In addition, it performs service call connection session management and control for service control signaling with SCP.

The CAP matching module provides a function to decode CAP signaling messages received from SCP / HLR through the SS7 network according to national / international standards in order to interoperate with SCP / HLR (Service Control Unit). Provides the function of encoding according to international standard and transmitting to SCP / HLR side. In addition, it performs service call connection session management and control functions for service control signaling with SCP / HLR.

MAP matching module provides the function to decode MAP signaling message received from SCP / HLR through SS7 network according to national / international standard in order to interwork with SCP / HLR (Service Control Unit), and decode MAP signaling message to domestic / international standard. Provides the function of encoding according to international standard and transmitting to SCP / HLR side. In addition, it performs service call connection session management and control functions for service control signaling with SCP / HLR.

INAP matching module provides the function to decode INAP signaling message received from SCP through SS7 network according to domestic / international standard for interworking with SCP (Service Control Unit), and to decode INAP signaling message according to national / international standard. Provides the function of encoding and sending to SCP. In addition, it performs service call connection session management and control for service control signaling with SCP.

SIP matching module provides the function to decode SIP signaling message received from AS through TCP / IP or UDP / IP according to national / international standard to interwork with application server device (AS), / Encode according to international standard and transmit to AS side. In addition, it performs service call connection session management and control for service control signaling with the AS.

Matching modules, such as Parlay, vXML, ccXML, JAIN, AU, etc., are used for signaling messages received via TCP / IP or UDP / IP from these devices to interoperate with AS (Application Server Device), Parlay GW, VXML Server device, etc It provides a function to decode according to national / international standards, and provides a function to encode signaling messages according to national / international standards and transmit them to these devices. In addition, the service call connection session management and control function for service control signaling processing.

In addition, the service control matching unit includes a processing module such as SS7 MTP1 / 2/3, TCAP processing module, which is the basic protocol for SS7 network interworking, and vXML, ccXML, MGCP or MEGACO AU Package, and Tone control package to facilitate service provision. can do.

10 is a block diagram showing the configuration of a basic call control unit of an IMG according to the present invention.

The Basic Call Control Part (BCCP) of the IMG according to the present invention provides a function for originating / terminating basic call control processing. In addition, the basic call control unit creates and maintains a call processing DB called call context for each call. The basic call controller can be largely composed of an originating call control module, a terminating call control module, a number translation module, a call session connection information management module, and the like.

Originating / Terminating call control module receives signaling message received from H323, SIP, R2, PRI, ISUP, MGCP, MEGACO signal matching module of call signal matching unit, H323, SIP, R2, PRI It provides call control processing functions such as ISUP, MGCP, MEGACO, and IVR (Interactive Voice Response).

The originating call control module is a module that handles incoming calls from other call processing devices, and provides incoming basic call session connection control and management, and terminating call control module It is a module that processes outgoing call when another call processing device is generated by the service control device or media server routing mechanism. It provides outgoing basic call session connection control and management function.

The call control module receives the signaling messages received from the H323, SIP, R2, PRI, ISUP, 3G-ISUP, MGCP, and MEGACO signal matching modules of the call signal matching unit, and receives the H323, SIP, R2, PRI, ISUP, MGCP, MEGACO , Call control processing functions such as IVR. That is, a module for handling incoming calls when another call processing device is generated, and provides incoming basic call session connection control and management functions.

The IVR call control module provides basic call session connection control and management to handle IVR call control when requested.

11 is a block diagram showing the configuration of a multimedia control unit of the IMG according to the present invention.

The multimedia control unit of the IMG according to the present invention largely includes a multimedia resource control unit (MRCP), a multimedia transmission control unit (MTCP, Multimedia Trnasport Control Part), and a multimedia resource processing unit (MRCP). do.

The multimedia resource controller receives a control message from a call controller or a service controller and provides a function for providing a resource requested by the call controller or a service controller. In addition, in order to efficiently manage and control resources, the resource management system calls a minimum unit for processing an audio or video as a channel, and a bundle of channels is called a SLOT, so that channel hunting and routing for each silent unit are performed. ) Function. The multimedia resource controller may include a resource control module and a resource management module.

The multimedia transmission control unit provides hardware and software processing function modules for delivering actual media traffic. The multimedia transmission control unit includes an ATM or Ethernet based RTP / RTCP (Real-Time Protocol / Real-Time Control Protocol) over UDP / IP, TCP / IP transmission matching module, 3GPP circuit-multimedia based H324M transmission matching module, and 3GPP ATM And an H324M transmission matching module, a media transmission matching module with an ASR / TTS / HTTP server via TCP / IP or UDP / IP, and an E1 / T1 or STM-1 based transmission matching module.

The multimedia resource processor provides a function of source coding or source decoding a voice or a video. In addition, it provides functions such as transcoding, multimedia mixing, interception, transmission, and recording between multimedia codecs. The multimedia resource processing unit may include a multimedia transcoding module, a multimedia mixing module, a multimedia listening module, a multimedia play / recording (IVR) module, and a multimedia routing / forwarding / switching module.

While specific embodiments of the present invention have been described so far, various modifications are possible without departing from the scope of the present invention.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims below, but also by the equivalents of the claims.

According to an IMG of the present invention and an operation method of the IMG, bearer capability information included in an ISDN (IDN User Part) IAM message received from a mobile communication terminal is read, and the bearer capability information is set to a multimedia mode. Only by controlling the opening of the multimedia channel between the mobile communication terminal and the VoIP terminal, it is possible to obtain the effect that can support the fallback (Fallback) between the 3G network and 2G network only by ISUP signaling.

In addition, according to the IMG of the present invention and the operation method of the IMG, when receiving a request to open a multimedia channel for a predetermined mobile communication terminal from a VoIP terminal, query for the terminal information and location information of the mobile communication terminal (Query) Is transmitted to a Home Location Register (HLR) and a response message corresponding to the query is received from the HLR, so that the mobile communication terminal is a mobile communication terminal supporting a 3G network and is located in the 3G network region. By controlling the opening of the multimedia channel between the VoIP terminal and the mobile communication terminal, it is possible to obtain the effect of performing the fallback of the multimedia channel to the speech channel before the start of the outbound call.

Further, according to the IMG of the present invention and the method of operating the IMG, when receiving a request for opening a multimedia channel for a predetermined mobile communication terminal from a VoIP terminal, the multimedia channel is first opened, and then a synchronization flag is received from the mobile communication terminal. By maintaining the multimedia channel when (Synchronization Flag) is detected, and controlling the fallback to the speech channel of the multimedia channel when the synchronization flag is not detected, the fallback can be controlled while maintaining the existing signaling. You can get it.

In addition, according to the IMG of the present invention and the operating method of the IMG, after the multimedia channel is opened between the 3G mobile communication terminal and the VoIP terminal, when the 3G mobile communication terminal moves out of the 3G network area, the 3G mobile communication terminal After analyzing the PCM according to the synchronization flag and recognizing that the 3G mobile communication terminal operates in the speech mode, the multimedia channel falls back to the speech channel, thereby distinguishing the 3G network and the 2G network in the same channel to establish a call connection. Controllable effects can be obtained.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above-described embodiments, which can be variously modified and modified by those skilled in the art to which the present invention pertains. Modifications are possible. Accordingly, the spirit of the present invention should be understood only by the claims set forth below, and all equivalent or equivalent modifications thereof will belong to the scope of the present invention.

Claims (12)

In the operating method of the interworking media gateway (IMG: Receiving an Initial Address Message (IAM) from a predetermined Mobile Switching Center (MSC), wherein the initial address message is transmitted from a predetermined originating mobile terminal to the mobile exchange for a predetermined incoming VoIP terminal. Corresponds to the transmitted call setup message (SETUP); Reading bearer capability information included in the initial address message; Controlling opening of a multimedia channel between the originating mobile communication terminal and the terminating VoIP terminal when the initial address message includes first bearer performance information set to a multimedia mode as a result of the reading; And Controlling opening of a speech channel between the originating mobile communication terminal and the destination VoIP terminal when the initial address message does not include the first bearer capability information as a result of the reading; Method of operation of an interworking media gateway comprising a. In the operating method of the interworking media gateway (IMG: Receiving an INVITE message for a predetermined terminating mobile communication terminal from a predetermined originating VoIP terminal, the invite message including multimedia channel open information; Transmitting an initial address message (IAM) corresponding to the invite message to a predetermined mobile switching center (MSC)-the mobile exchange corresponding to the initial address message to the destination mobile communication terminal; Send a call setup message (SETUP); Receiving a predetermined address complete message (ACM) from the mobile switch, the address complete message corresponding to an alerting of the called mobile communication terminal according to the call setup message; Reading an optional field of the address completion message; Controlling opening of a multimedia channel between the originating VoIP terminal and the called mobile communication terminal when the first bearer performance information set to the multimedia mode is included in the additional field of the address completion message as a result of the reading; And Controlling opening of a speech channel between the originating VoIP terminal and the called mobile communication terminal when the first bearer performance information is not included in an additional field of the address completion message as a result of the reading; Method of operation of an interworking media gateway comprising a. The method of claim 2, The mobile switch corresponds to the alloting of the called mobile communication terminal so that the called mobile communication terminal is a terminal capable of opening the multimedia channel and is located in an area where the multimedia channel can be opened. And recording the first bearer performance information in an additional field of. The method of claim 2, The step of controlling the opening of the multimedia channel between the calling VoIP terminal and the called mobile communication terminal, Continuously setting a synchronization flag to the destination mobile communication terminal at each level of the H223 when setting the H223 level with the destination mobile communication terminal; And Completing setting of the H223 level when the flag received from the destination mobile communication terminal for each level is the same as the transmitted flag; Method of operation of an interworking media gateway comprising a. In the operating method of the interworking media gateway (IMG: Receiving an INVITE message for a predetermined terminating mobile communication terminal from a predetermined originating VoIP terminal, the invite message comprising multimedia channel open information; Transmitting a query for information and location of the called mobile communication terminal to a predetermined home location register (HLR); Receiving predetermined response information from the home location register; Reading the response information; Controlling opening of a multimedia channel between the calling VoIP terminal and the called mobile terminal when the called mobile terminal satisfies a first condition and a second condition at the same time, the first condition being the called condition. A condition in which a mobile communication terminal is a terminal capable of opening the multimedia channel, and the second condition is a condition in which the called mobile communication terminal is located in an area in which the multimedia channel can be opened; And Controlling opening of a speech channel between the calling VoIP terminal and the called mobile terminal when the called mobile terminal does not satisfy the first condition and the second condition at the same time. Method of operation of an interworking media gateway comprising a. The method of claim 5, The step of controlling the opening of the multimedia channel between the calling VoIP terminal and the called mobile communication terminal, Continuously setting a synchronization flag to the destination mobile communication terminal at each level of the H223 when setting the H223 level with the destination mobile communication terminal; And Completing setting of the H223 level when the flag received from the destination mobile communication terminal for each level is the same as the transmitted flag; Method of operation of an interworking media gateway comprising a. In the operating method of the interworking media gateway (IMG: Receiving an INVITE message for a predetermined terminating mobile communication terminal from a predetermined originating VoIP terminal, the invite message including multimedia channel open information; Controlling opening of a multimedia channel between the calling VoIP terminal and the called mobile terminal; Transmitting a synchronization flag corresponding to the multimedia channel to the called mobile communication terminal; Maintaining the open of the multimedia channel when receiving a flag corresponding to the synchronization flag transmission from the called mobile communication terminal; And Controlling a fallback to a speech channel of the multimedia channel when a flag corresponding to the synchronization flag transmission is not received from the called mobile communication terminal; Method of operation of an interworking media gateway comprising a. The method of claim 7, wherein The step of keeping the multimedia channel open, Continuously setting a synchronization flag to the destination mobile communication terminal at each level of the H223 when setting the H223 level with the destination mobile communication terminal; And Completing setting of the H223 level when the flag received from the destination mobile communication terminal for each level is the same as the transmitted flag; Method of operation of an interworking media gateway comprising a. In the operating method of the interworking media gateway (IMG: Receiving an Initial Address Message (IAM) from a predetermined Mobile Switching Center (MSC), wherein the initial address message is transmitted from a predetermined originating mobile terminal to the mobile exchange for a predetermined incoming VoIP terminal. Corresponds to the transmitted call setup message (SETUP); Reads bearer capability information included in the initial address message, and when the initial address message includes first bearer capability information set as a multimedia channel, a multimedia channel between the originating mobile communication terminal and the terminating VoIP terminal. Controlling the opening of the; Analyzing PCM data corresponding to the originating mobile communication terminal when the multimedia channel is maintained; And Controlling the fallback of the multimedia channel to the speech channel when it is determined that the originating mobile communication terminal has moved to an area where the multimedia channel cannot be opened. Method of operation of an interworking media gateway comprising a. The method of claim 9, The outgoing mobile communication terminal supports both 3G mobile communication network and 2G mobile communication network, and when moving from the 3G mobile communication network to the 2G mobile communication network, the hand-off (Hand-Off) to the 2G mobile communication network, characterized in that How the working media gateway works. The method of claim 9, When maintaining the multimedia channel, the step of analyzing the PCM data corresponding to the outgoing mobile communication terminal, Detecting a synchronization flag corresponding to the originating mobile communication terminal according to the maintenance of the multimedia channel; And If the synchronization flag is not detected from the calling mobile terminal, determining that the calling mobile terminal has moved to an area where the multimedia channel cannot be opened. Method of operation of an interworking media gateway comprising a. A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 1 to 11.

Images