WO2008000157A1

WO2008000157A1 - A method and device for achieving the parallel call function of the multimedia call

Info

Publication number: WO2008000157A1
Application number: PCT/CN2007/001938
Authority: WO
Inventors: Geng Wang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-06-20
Filing date: 2007-06-20
Publication date: 2008-01-03
Also published as: CN100574232C; CN101094130A

Abstract

A method and device for achieving the parallel call function of the multimedia call. The said method comprises that: when a user performing the first multimedia session initiates a call holding HOLD service, the MSC SERVER informs to interrupt the media stream channel of the first session; and the MSC SERVER uses the bear of the side which has initiated the HOLD to establish the media stream channel between the user initiating the HOLD and the opposite side user of the new session to achieve the second session.

Description

Method and device for implementing parallel call function of multimedia call

The present invention relates to the field of communications, and in particular, to a method and apparatus for implementing a parallel call function for a multimedia call. Background technique

CS DOMAIN Multimedia call service is an important service in the third generation mobile communication system, and it is one of the landmark services of the third generation mobile communication. This kind of business enables users to see the image of the other party while making a voice call, which is a business with important practical application value.

The WCDMA third-generation mobile communicator began with the R4 version, defining a system architecture to perform a variety of services, including video telephony. The basic network elements included in this system architecture are: user equipment UE, WCDMA system base station NODE B, WCDMA system base station controller RNC, MGW and MSG SERVER. A basic networking relationship of the system architecture is shown in Figure 1.

UE: The terminal device used by the user, often referred to as a mobile phone.

NODE B: Mainly responsible for wireless signal transmission and reception.

RNC: Mainly responsible for the management of the wireless access network.

MGW: Mainly responsible for the management of various bearer resources and the actual operation of the connection network.

MSC SERVER: It is the core of the system. It is mainly responsible for the logical control of various services, uniformly scheduling various network resources, and generating call records.

a interface: air interface signaling channel.

b interface: Business data channel.

c interface: Media gateway control signaling channel.

d interface: BICC/ISUP/SIP signaling channel.

Based on the above system architecture, the basic services provided by the WCDMA third generation mobile communication system are divided into two types: one is a bearer service, and the other is a telecommunication service. Bearer services are only available to users A service data channel of a certain quality (such as bandwidth, synchronous asynchronous, etc.), regardless of what is transmitted in the channel; the telecommunication service provides both the service data channel between users and the content transmitted in the channel. Therefore, for example, the bearer service only provides the user with a road, and the user can transport whatever he wants to transport on the road, and the telecommunication service provides a road for the user, and also stipulates what the user transports.

Further, the WCDMA third generation mobile communication system provides a service called Multimedia call (multimedia call), which can complete the voice call function, the data communication function, and the videophone function.

In order to implement the above multimedia call service, the following signaling, protocols and terminals are needed:

1. Call control signaling: There are two types, one is air interface signaling for terminal and network side equipment for call control, and the other is call control signaling (ie, relay signaling) between network devices. They are used to deliver messages such as originating, ringing, answering, disconnecting, etc., as well as negotiating to establish bearer service channels.

2. H.245 Multimedia Communication Control Protocol: The H.245 protocol defined by ITU-T defines how to establish multiple media stream logical channels through a series of negotiation within a single service data channel. The terminal capability negotiation process is defined ( After the process is performed, both parties can know the media types supported by the other party, such as voice, video, etc., master-slave discrimination (determination of master-slave relationship), and reuse control information interaction.

(To support simultaneous delivery of multiple media streams in a single service channel), open and close media stream logical channels, and so on.

3. H.223 low bit rate multimedia communication multiplexing protocol: The H.223 protocol developed by ITU-T enables communication parties to simultaneously transmit multiple voice, video and data media streams using a single service data channel. It needs to be combined with H.245. Collaborative operation. Referring to FIG. 2, it is a structural hierarchy diagram of H.223. The application layer (that is, the service object of H.223) is a module that provides and receives various voice, video or data (for example: a microphone of a mobile terminal, The display or camera), the lowest layer, the physical layer is a service data channel. As can be seen from Figure 2, H.223 supports the transmission of multiple media streams using the single-nano physical service channel.

4, 3G-324M terminal is a terminal defined by 3GPP for multimedia call service, as shown in Figure 3, it mainly includes three parts: First, the media processing module, including: voice, video And the data processing part; the second is the system control module, which is responsible for interacting with the network side, performing call control, and on the other hand, performing operations such as establishing and releasing logical channels with the peer device through the H.245 protocol; The 223 protocol processing module is responsible for multiplexing and decomposing voice, video, data, and H.245 control information.

There are currently two implementations of the aforementioned multimedia call service.

Solution 1: In the circuit domain of WCDMA third-generation mobile communication system, the establishment of multimedia call is divided into two phases: The first phase is to complete the call connection in the manner of data service and establish the bearer service channel between users, the second phase, After the response, the user establishes a signaling interaction of the media stream in an in-band manner in the bearer service channel, and determines a voice, video, and/or data media stream to be established, thereby establishing a multimedia call. The operation of establishing the media stream in the second phase is completely carried out in the band, and the related signaling does not pass through the MSC SERVER. Therefore, the MSC SERVER does not know the establishment of the media stream channel completely, and does not know which of the voice, video or data the user specifically performs. Media type communication.

Solution 2: The implementation method of another multimedia call in the circuit domain of the WCDMA third generation mobile communication system can also change the process of media stream negotiation from in-band to out-of-band. There are two basic methods to implement by extending air interface signaling and relay signaling: One method is to allow air interface signaling and relay signaling to support the delivery of H.245 messages, and the user can basically press the existing multimedia call. The method establishes a multimedia call. The main difference is that the H.245 message is transmitted by out-of-band. The other method is to add a cell for media stream negotiation in the air interface signaling and the relay signaling, and initiate a call message. It carries information such as the type, number of pieces, codec, and multiplexing control parameters of the media stream to be established by the calling party. Let the network or the called party return the received media stream information and the selected codec and the like in the ringing message or the call progress message, and establish a media stream when the call is answered, and realize the function of the multimedia call.

The following describes the supplementary services and functions related to the multimedia call service.

The call service of the voice service maintains the supplementary service: the service enables the user to suspend the other party during the voice call, and the party that initiates the call hold service can establish a new call with the other party by using the established air interface bearer. The party that initiated the call to keep the service can switch back to The user who originally made the call makes a call and suspends the newly established call. A description of this service can be found in 3GPP TS 22.083.

The function of Fallback (Fallback) means that the user tries to initiate a service that he or she expects to give to the other party. However, because the network or the other party does not support the service, the service is changed to a service that everyone can accept. Features.

Multi-call (MC) service (see 3GPP TS 22.135): refers to a service in which a user can perform multiple calls simultaneously using one terminal, and each call utilizes a separate air interface to carry resources.

In the process of the invention, the inventor has found that the MC service implements the function of multiple terminals simultaneously performing multiple calls, but usually the user only talks with one peer at the same time, and each call utilizes independent air interface bearer resources. Obviously, in this case, the MC service causes the air port to carry the waste of resources. Summary of the invention

The embodiment of the invention provides a method and a device for implementing a parallel call function of a multimedia call, so that the WCDMA circuit domain supports the use of the air interface carrying resources of the established multimedia call to make a new call.

The method of the embodiment of the present invention includes the following steps: when a user who is in the first multimedia session initiates a call to hold the HOLD service, the MSC SERVER instructs to disconnect the media stream channel of the first session; and the MSC SERVER utilizes the initiated HOLD side. The bearer establishes a media stream channel between the user who initiates the HOLD and the user of the new session to implement the second session.

A mobile switching center server according to an embodiment of the present invention includes: a receiving unit, configured to receive a call hold HOLD service initiated by a user who is performing a first multimedia session; and an indication unit, configured to receive the HOLD at the receiving unit In the service, the media stream channel of the first session is disconnected from the connection; the connection unit is configured to establish a media stream channel between the user who initiates the HOLD and the user of the new session by using the bearer that initiates the HOLD-side, to implement the Two sessions.

The method of the embodiment of the present invention can complete the establishment of a new session by using the media stream channel that initiates the HOLD-side in the WCDMA circuit domain, and avoids that each call uses an independent air interface to bear resources. The port carries the problem of wasted resources. DRAWINGS

1 is a schematic structural diagram of an existing WCDMA communication system;

Figure 2 is a schematic diagram showing the structure of the existing H.223;

Figure 3 is an internal structure diagram of a conventional 3G-324M terminal;

4 is a flow chart of steps of a method according to an embodiment of the present invention;

FIG. 5 is a signaling flowchart of a method example 1;

6 is a signaling flowchart of method example 2;

Figure 7 is a signaling flow chart of method example three. detailed description

In order to enable the WCDMA circuit domain to support the use of the air interface carrying resources of the established multimedia call to make a new call, the embodiment of the present invention provides a method for implementing the parallel call function of the multimedia call. Referring to FIG. 4, the following main steps are included:

S1. The user who is performing the first multimedia session initiates the HOLD service.

Based on the technical problem to be solved by the embodiment of the present invention, it is assumed that a user initiates a HOLD operation during the first multimedia call.

52. The MSC SERVER processes the first session.

This step includes the processing of the signaling layer and the processing of the media stream channel.

The signaling layer of the HOLD service is processed according to the signaling interaction process of the HOLD supplementary service of the voice service.

The disconnection processing of the media stream channel is performed by the MSC SERVER controlling the MGW to disconnect the media stream channel of the session from the HOLD-side (ie, the HOLD user to the media stream channel of the MGW) and initiate the HOLD. The bearer on the side (ie, the media stream channel that initiates the HOLD user to the MGW).

53. Establish a second session between the user who initiates the HOLD and the user of the new session. The second session is established by the MSC SERVER to instruct the media stream channel between the newly created MGW and the new session peer user; after that, the MSC SERVER controls the MGW to connect the media stream channel on the opposite side of the new session with the HOLD side. The corresponding media stream channel is connected to establish a second session.

Depending on the originator of the second session (including: the user who initiated the HOLD and the new session peer user), and the second session type initiated (including: multimedia call and voice call), the following four cases are introduced one by one.

Case 1: If the second session initiated by the user who initiates the HOLD to the new session peer user is a multimedia call, the MSC SERVER cannot determine whether the new session peer supports the multimedia call, and is not sure whether the new session peer user is willing to accept the multimedia call. When the MSC SERVER receives a new call request, there are two ways to process the call to the new session peer user:

Method 1: Try one by one.

That is, the MSC SERVER first carries the multimedia calling capability, and initiates a multimedia call to the new session peer user; if the new session peer supports the multimedia call and is willing to accept the multimedia call, the media stream channel of the MGW to the new session peer user is established; After that, the MSC SERVER controls the MGW to connect the media stream channel on the opposite side of the new session with the corresponding media stream on the HOLD side (including: voice stream and media stream) to complete the user who initiates the HOLD service and the new session peer. A multimedia session between users. If the new session peer does not support the multimedia call, or is unwilling to accept the multimedia call, the call setup fails.

After the MSC SERVER learns that the multimedia call fails to be established, it carries the voice call capability again, and initiates a voice call to the new session peer user. If the new session is willing to accept the voice call, the voice bearer of the MGW to the new session peer user is established. Channel; after that, the MSC SERVER controls the MGW to connect the voice bearer channel on the opposite side of the new session with the media channel on the side that initiates the HOLD.

words.

Method 2: Fallback mode.

If the system supports the Fallback function, the MSC SERVE carries both the multimedia calling capability and the voice calling capability to initiate a call to the new session peer user; if the new session peer supports more When the media calls and is willing to accept the multimedia call, the media stream channel of the MGW to the new session peer user is established; after that, the MSC SERVER controls the MGW to correspond to the media stream channel on the opposite side of the new session and initiates the HOLD-side. Media stream connections (including: voice streams and media streams) to complete a multimedia session between the user initiating the HOLD service and the new session peer user. If the new session peer does not support the multimedia call, or is only willing to accept the voice call, it will establish the voice 7-channel of the MGW to the new session peer user; after that, the MSC SERVER controls the MGW to voice the new session to the opposite end. The bearer channel is connected to the voice stream in the media channel on the HOLD side to complete the voice session between the user initiating the HOLD service and the new session peer user.

Case 2: If the second session initiated by the user who initiates the HOLD to the new session peer user is a voice call, the MSC SERVER directly carries the voice call capability and initiates a call to the new session peer user. If the new session peer is willing to accept the voice call, the voice bearer channel of the MGW to the new session peer user will be established; after that, the MSC SERVER controls the MGW to connect the voice bearer channel on the opposite side of the new session with the HOLD side. A voice stream connection in the media channel to complete a voice session between the user initiating the HOLD service and the new session peer user.

Case 3: If the new session peer user initiates a second session to the user who initiated the HOLD, the second session is first determined by the MSC SERVER. In this case, the MSC SERVER determines that the second session is a multimedia call. After that, there are three ways to process the MGW to the new session peer user, and the MGW and the media stream channel of the HOLD user:

Manner 1: The number and type of media streams of the first multimedia session take precedence.

The MSC SERVE takes the intersection of the number and type of media streams of the second session and the number and type of media streams of the first multimedia session; and then establishes, by the intersection, the media stream channel of the MGW to the new session peer user. The non-intersecting portion of the media stream of the second session will be rejected by the MSC SERVER. Then, the MSC SERVER controls the MGW to connect the media stream channel on the opposite side of the new session with the corresponding media stream channel on the HOLD side to complete the multimedia session between the user initiating the HOL service and the user in the new session.

Method 2: The number and type of media streams in the second session take precedence.

According to the number and type of media streams in the second session, the MGW is established correspondingly to the new session peer user. The media stream channel; and supplementing the media stream channel of the user who initiated the HOLD with the number and type of the media stream of the second session, so that the number and type of media stream channels of the user who initiates the HOLD to the MG at least include the second The number and type of media streams for the session. After that, the MSC SERVER controls the MGW to connect the MGW to the media stream channel of the new session peer user, and the original media stream channel that initiates the HOLD-side and the supplemental established media stream channel to complete the user and the new session for initiating the HOLD service. A multimedia session between peer users.

Manner 3: In the new session, the peer user negotiates media with the user who initiated the HOLD, and establishes a media stream channel according to the negotiation result.

The new session peer user and the user who initiates the HOLD use the MSC SERVER as a proxy to negotiate the media stream channel that needs to be established in the second session, and the MSC SERVER controls the MGW to establish a media stream channel between the MGW and the new session peer user according to the negotiation result, and The MSC SERVE controls the MGW to add or delete the media stream channel between the MGW and the user who initiates the HOLD (ie, the original media stream channel between the MGW and the user who initiated the HOLD can be reused, and the excess media stream channel can be removed); after that, the MSC The SERVER controls the MGW to connect the media stream channels at both ends.

Case 4: If the new session peer user initiates a second session to the user who initiated the HOLD, the second session is first determined by the MSC SERVER. In this case, the MSC SERVER determines that the second session is a voice call. The MSC SERVER directly indicates the establishment of the voice bearer channel of the MGW to the new session peer user; after that, the MSC SERVER controls the MGW to connect the voice bearer channel on the opposite side of the new session with the voice stream channel in the media channel on the HOLD side. Complete the voice session between the user who initiated the HOLD service and the new session peer user.

When the second session is a multimedia call and the setup is successful, the user can add, reduce, or modify the media stream as needed. So far, the bearer on the HOLD-side is used to establish an overview of the second session between the user who initiated the HOLD and the user of the new session.

While the second session is established, the bearer on the HOLD side can be reserved; and after the bearer on the HOLD side is retained, in order to enhance the user experience, the media stream is played by the HOLD user who is waiting to resume the call state.

S4. The user who initiates the HOLD wants to switch back to the first multimedia session. S5. The MSC SERVER indicates to restore the first session, and complete HOLD processing or disconnection processing on the second session.

Referring to the signaling level of the completion of the signaling interaction process of the HOLD supplementary service of the voice service.

The processing of the media stream channel is controlled by the MSC SERVER according to the establishment of the media stream channel of the first session, and the MGW can restore the channel of the media stream of the first session and the network connection; and according to the operation of the user, the second is completed accordingly. HOLD processing or disconnection processing of the session.

If the second session is processed by HOLD, the user can repeatedly switch between the first multimedia session and the second session.

The embodiment of the invention further provides a mobile switching center server, comprising: a receiving unit, an indicating unit and a connecting unit.

a receiving unit, configured to receive a user-initiated call hold HOLD service that is in the first multimedia session;

And an indicating unit, configured to: when the receiving unit receives the HOLD service, instruct to disconnect the media stream channel of the first session;

The splicing unit is configured to establish a media stream channel between the user initiating the HOLD and the user in the new session by using the bearer on the HOLD side to implement the second session.

The following is further specifically described by three examples.

Method Example 1: Calling User 1 (UE1) establishes a multimedia session with User 2 in a multimedia call mode; during the call, User 1 maintains a multimedia session with User 2 and initiates a multimedia call with User 3; 3 Support and willing to accept the multimedia call. See Figure 5, which includes the following main steps:

(Note: The process of taking the roaming number in Figure 5 is omitted.)

1. User 1 and user 2 complete the process of establishing a multimedia call.

In the process of establishing a media stream channel between user 1 and user 2, the path that the H.245 message passes is UE1 UE2, MGW, MSC, MGW, UE2/UE1. TCS, MUXTBSND, The OLCs are all H.245 messages, which are sent by the terminal capability, sent by the multiplex table, and opened by the logical channel. This figure omits the response message. The response message of the above message is required according to H.245. When receiving After the end user receives the above message, the response message returned by the receiving end can be returned in the opposite direction of the original message path, the same below. (Note: 1. The order of sending the above TCS, MUXTBS D, OLC and other messages is not limited to the order shown in the figure; 2. Figure 5 shows the master-slave discrimination process of H.245.)

2. When the user enters the multimedia call state, the user 1 initiates a call hold to the user 2. The MSC SERVER controls the MGW to disconnect the bearer between UE1 and UE2, and can play the media stream to the user 2 to make it comfortable to wait. User 1 initiates a new multimedia call to User 3, and the call is accepted.

3. The MSC SERVER and the user 3 establish a media stream channel negotiation, and control the MGW to establish a media stream channel with the user 3. Each time a channel is successfully established, the channel is connected to the corresponding media stream channel of the UE1. User 1 can also send an open logical channel message to user 3 through MGW and MSC SERVER according to its needs, and initiate a new media stream channel with user 3 (Note: not shown in Figure 5).

4. When the user ends the call, the disconnection of the call is performed.

(Note: This method example illustrates the scenario of an intra-office call, but the technical content expressed in this method example is also applicable to the scenario of inter-office calls.)

Method Example 2: The calling user 1 (UE1) establishes a multimedia session with the user 2 in a multimedia call mode; during the call, the user 1 maintains the multimedia session with the user 2 and initiates a multimedia call with the user 3; The terminal of 3 does not support multimedia calls. See Figure 6 for the following main steps:

(Note: The process of taking the roaming number in Figure 6 is omitted.)

1. Same as method example one.

2. When the user enters the multimedia call state, the user 1 initiates a call hold to the user 2. The MSC SERVER controls the MGW to disconnect the bearer between the UE1 and the UE2, and can play the media stream to the user 2 to make it comfortable to wait. User 1 initiates a new multimedia call to user 3, and MSC SERVER initiates a call in a manner that supports Fallback when forwarding a call to UE3. Since UE3 does not support multimedia call, Finally, the call is established in the form of voice, so the voice bearer is established between the MGW and the UE3.

3. MSC SERVER Control The MGW connects the voice media stream channel of UE1 with the voice bearer of UE3, so that user 1 can make a voice call with user 3.

4. When the user ends the call, the disconnection of the call is performed.

Method Example 3: On the basis of the method instance 1, the user 1 initiates and completes the process of restoring the call with the user 2 while maintaining the call with the user 3. See Figure 7 for the following main steps:

(Note: The process of taking the roaming number in Figure 7 is omitted.)

1. The process before the line is removed as shown in the first example of the method.

2. The user 1 initiates the operation of the user 3 to the MSC SERVER. The MSC SERVER controls the MGW to disconnect the media stream channel between the user 1 and the user 3, and can play the media stream to the user 3 to make the user 3 comfortable to wait.

3. The user 1 initiates the operation of restoring the call with the user 2 to the MSC SERVER, and the MSC SERVER controls the MGW to restore the media stream channel connection relationship between the user 1 and the user 2.

4. When the user ends the call, the disconnection of the call is performed.

In summary, in the embodiment of the present invention, when the user performing the first multimedia session initiates the HOLD service, the MSC SERVER controls the MGW to disconnect the media stream channel of the first session from the bearer on the HOLD side ( That is, the media stream channel of the HOLD user to the MGW and the bearer that initiates the HOLD side (ie, the media stream channel that initiates the HOLD user to the MGW). For the HOLD-side, the media stream channel can be reserved, and the media stream can be played for the user experience; for the HOLD-side, the MSC SERVER uses the media stream channel that initiates the HOLD-side to establish the user who initiates the HOLD. The new session will live the media stream channel between the peer users to implement the second session. If the user who initiates the HOLD needs to switch back to the first session, the MSC SERVER may be based on the media of the first session. The establishment of the body flow channel, indicating the restoration of the first session.

In the embodiment of the present invention, the establishment of a new session can be completed by using the media stream channel on the HOLD side of the WCDMA circuit domain, which avoids the problem that the air interface bearer resources are wasted by using the independent air interface bearer resources for each call. The spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of the inventions

Claims

Rights request

A method for implementing a parallel call function for a multimedia call, comprising the steps of:

When the user in the first multimedia session initiates a call to hold the HOLD service, the MSC SERVER instructs to disconnect the media stream channel of the first session;

The MSC SERVER uses the bearer on the HOLD-side to establish a media stream channel between the user who initiates the HOLD and the user of the new session to implement the second session.

2. The method according to claim 1, wherein, when the user who is performing the first multimedia session initiates the HOLD service, the signaling layer of the multimedia call HOLD service is completed by the signaling interaction process of the voice HOLD service. Processing.

The method according to claim 1, wherein the establishing a media stream channel of the second session between the user initiating the HOLD and the new session peer user comprises the following steps:

A. The MSC SERVER controls the new media stream channel between the MGW and the new session peer user;

B. MSC SERVER Control The MGW connects the media stream channel on the opposite side of the new session with the corresponding media stream channel on the HOLD side to establish a media stream channel required for the second session.

The method of claim 3, wherein the step A further comprises: adding, deleting, or deleting a media stream channel between the MSC SERVER and the initiating HOLD user.

The method of claim 3, wherein if the user initiating the HOLD initiates a multimedia call to the new conference peer user, the step A includes the following sub-steps:

All, the MSC SERVER carries the multimedia calling capability, and initiates a call to the new session peer user; A12 The new session peer decides whether to accept the multimedia call, and if yes, proceeds to step A13; otherwise, proceeds to step A14;

A13, establishing a media stream channel of the MGW to the new session peer user, and proceeding to step B;

A14. The MSC SERVER carries the voice call capability, and initiates a call to the new session peer user. A15. Set up the MGW to the voice bearer channel of the new session peer user, and go to step B.

6. The method according to claim 5, wherein in step A12, a new session is used The terminal and/or network capabilities of the peer, and the willingness of the new session peer to decide whether to accept the multimedia call.

7. The method according to claim 5, wherein in step A13, after proceeding to step B, the MSC SERVER controls the MGW to connect the media stream channel on the opposite side of the new session with the corresponding media on the side that initiates the HOLD. The stream channel is connected to complete a multimedia session between the user initiating the HOLD service and the new session peer user.

8. The method according to claim 5, wherein in step A15, after proceeding to step B, the MSC SERVER controls the MGW to circulate the voice bearer channel on the opposite side of the new session and the media on the HOLD side. The voice stream channel in the channel is connected to complete the voice session between the user who initiates the HOLD service and the new session peer user.

A21. The MSC SERVER carries the multimedia calling capability and the voice calling capability, and initiates a call to the new session peer user;

A22, if the new session peer decides to accept the multimedia call, then proceeds to step A23; otherwise, proceeds to step A24;

A23. Establish a media stream channel of the MGW to the new session peer user, and go to step B. A24. Establish an MGW to the voice bearer channel of the new session peer user, and go to step B.

10. The method of claim 9, wherein in step A22, determining whether to accept the multimedia call is based on the terminal and/or network capabilities of the new session peer and the wishes of the new session peer user.

The method according to claim 9, wherein in step A23, after proceeding to step B, the MSC SERVER controls the MGW to connect the media stream channel on the opposite side of the new session with the corresponding media on the side of the HOLD. The stream channel is connected to complete a multimedia session between the user initiating the HOLD service and the new session peer user.

12. The method according to claim 9, wherein in step A24, after proceeding to step B, the MSC SERVER controls the MGW to initiate a voice bearer channel on the opposite side of the new session. The voice stream channel in the media channel on the HOLD side is connected to complete a voice session between the user who initiates the HOLD service and the user of the new session peer.

13. The method according to claim 4, wherein if the new session peer user initiates a second session to the user who initiated the HOLD, the step A includes the following sub-steps:

A31, if the MSC SERVER determines that the second session is a multimedia call, then proceeds to step A32; if the MSC SERVER determines that the second session is a voice call, then proceeds to step A33;

A32, establishing an MGW to the media stream channel of the new session peer user, and correspondingly adding or deleting the MGW to the media stream channel of the HOLD user, and proceeding to step B;

A33. Establish a voice bearer channel of the MGW to the peer of the new session, and go to step B.

The method according to claim 13, wherein the step A32 further comprises the following steps:

- the MSC SERVER takes the intersection of the number and type of media streams of the second session and the number and type of media streams of the first multimedia session;

- establishing, by the intersection, a media stream channel corresponding to the MGW to the new session peer user; and deleting the media stream channel of the first multimedia session other than the intersection.

The method of claim 14, wherein after the step B is performed, the MSC SERVER controls the MGW to connect the media stream channel on the opposite side of the new session with the corresponding media stream channel on the HOLD side to complete A multimedia session between the user who initiated the HOLD service and the new session peer user.

- establishing, according to the number and type of media streams of the second session, a media stream channel of the MGW to the new session peer user;

- supplementing the media stream channel of the MGW to the user who initiated the HOLD by the number and type of media streams of the second session.

The method according to claim 16, wherein after proceeding to step B, the MSC SERVER controls the MGW to transfer the MGW to the media stream channel of the new session peer user, and initiates the HOLD side. The original media stream channel and the supplemental established media stream channel are correspondingly connected to complete a multimedia session between the user who initiates the HOLD service and the new session peer user.

- The user who initiated the HOLD and the new session peer user conduct media negotiation through the MSC SERVER, and establish a media stream channel of the MGW to the new session peer user according to the negotiation result, and correspondingly add or delete the MGW to the media stream channel that initiates the HOLD user.

The method according to claim 18, wherein after the step B is performed, the MSC SERVER controls the MGW to connect the media stream channel on the HOLD side to the media stream channel on the opposite side of the new session to complete the connection. A multimedia session between the user who initiated the HOLD service and the new session peer user.

The method according to claim 13, wherein in step A33, after proceeding to step B, the MSC SERVER controls the MGW to transmit the voice bearer channel on the opposite side of the new session and the media channel on the HOLD side. The voice stream channel is connected to complete the voice session between the user initiating the HOLD service and the new session peer user.

21. The method of claim 7, 11, 13, 15, 17, or 19, wherein after the second session is successfully established, the user can add, reduce, or modify the media stream as needed.

22. A mobile switching center server, comprising:

The splicing unit is configured to establish a media stream channel between the user who initiates the HOLD and the user of the new session by using the bearer that initiates the HOLD-side to implement the second session.