CN102131069A - Video call method, system, terminal and mobile switching center - Google Patents

Abstract

The embodiment of the present invention discloses a video call method, system, terminal and mobile switching center, wherein, a video call method includes the following steps: receiving a first video call VP call request from the calling terminal; notifying the called terminal that there is VP call, so that the called terminal performs 3G location update after receiving the notification, and camps in the CS domain on the 3G network; initiates a second VP call request to the called terminal, so that the called terminal performs VP services according to the second VP call request. Through the embodiment of the present invention, the VP service can be implemented for the called terminal user whose CS domain preferentially resides in the 2G network.

Description

Video call method, system, terminal and mobile switching center

technical field

The invention relates to the technical field of communication, in particular to a video calling method, system, terminal and mobile switching center.

Background technique

The VP (Video Phone, video phone) service is a standard service of 3G (3rd generation mobile communication), carried by the CS (Circuit Switch, circuit switched) domain of 3G. 2G usually does not support CS domain-based VP services. VP is sometimes called VT (Video Telephony), 3G communication technology such as WCDMA, TD-SCDMA, 2G such as GSM.

Restricted by various conditions, the construction of 3G network cannot be completed in a short period of time, and the 2G network will not disappear in a short period of time. Therefore, 2G and 3G networks will coexist for a long time. In this long-term coexistence stage, in order to obtain a better communication experience, the existing single-card 3G terminals (such as mobile phones) generally also support 2G. For the convenience of explanation, this type of single-card terminal supports both 2G and 3G. It is a 2G/3G dual-mode terminal. When a 2G/3G dual-mode terminal is working, it generally prefers to reside on 3G. At this time, the CS domain of the 3G network carries the VP service.

In the process of realizing the present invention, the inventor finds that the prior art has at least the following disadvantages:

In actual use, 2G/3G dual-mode terminals will preferentially reside in the CS domain on the 2G network for some reasons (such as better call quality). At this time, since the 2G CS domain cannot carry VP services, therefore, End users will not be able to use VP services.

Contents of the invention

Embodiments of the present invention provide several video calling methods, systems, terminals and mobile switching centers, wherein:

The embodiment of the present invention provides a video phone calling method, comprising the following steps:

receiving the first video phone VP call request of the calling terminal;

Notifying the called terminal that there is a VP call, so that the called terminal performs 3G location update after receiving the notification, and resides in the CS domain to the 3G network;

Initiating a second VP call request to the called terminal, so that the called terminal performs a VP service according to the second VP call request.

The embodiment of the present invention also provides a video phone call method, including the following steps:

Receiving a notification that the called terminal has a video phone VP call, and the notification is sent by the network after receiving the first VP call request of the calling terminal;

Perform 3G location update and reside in the CS domain to the 3G network;

receiving a second VP call request sent by the network, and performing a VP service according to the second VP call request.

The embodiment of the present invention also provides a video phone call method, including the following steps:

Determine whether it is in a 3G service area, if so, initiate a 3G location update, and place the CS domain in the 3G network;

Send the first VP call request to the network, so that after the network receives the first VP call request, it notifies the called terminal that there is a VP call, and the called terminal performs 3G location update after receiving the notification, and resides in the CS domain on the 3G network ; The subsequent network initiates a second VP call request to the called terminal, so that the terminal performs a VP service according to the VP call.

The embodiment of the present invention also provides a video phone call system, including:

2G/3G mobile switching center MSC, calling mobile switching center MSC, and location home register HLR, wherein the 2G/3G MSC indicates that the MSC can handle both 2G CS services and 3G CS services;

The calling MSC is used to receive the first VP call request of the calling terminal, and send a second VP call request to the 2G/3G MSC;

The 2G/3G MSC is used to notify the called terminal that there is a VP call after receiving the second VP call request, so that the called terminal passes the 2G/3G MSC after receiving the notification, or passes the 2G /3G MSC and the HLR perform 3G location update, and reside in the CS domain to the 3G network;

The 2G/3G MSC is further configured to initiate a third VP call request to the called terminal after the called terminal CS domain camps on the 3G network, so that the called terminal The call requests the VP service.

The embodiment of the present invention also provides a video phone call system, including:

2G mobile switching center MSC, 3G mobile switching center MSC, calling mobile switching center MSC, location home register HLR;

The calling MSC is used to receive the first VP call request of the calling terminal, and send the second VP call request to the 2G MSC;

The 2G MSC is used to notify the called terminal that there is a VP call after receiving the second VP call request, so that the called terminal performs 3G location update through the 3G MSC and the HLR after receiving the notification, and will The CS domain resides in the 3G network;

The embodiment of the present invention also provides a terminal, including:

A receiving unit, a location updating unit, and a service executing unit;

The receiving unit is used to receive a notification that the called terminal has a video phone VP call, and the notification is sent by the network after receiving the first VP call request of the calling terminal;

The location update unit is used for the receiving unit to update the 3G location after receiving the notification, and to reside the CS domain in the 3G network;

The receiving unit is further configured to receive a second VP call request sent by the network after the CS domain resides in the 3G network;

The service execution unit is configured to perform a VP service according to the second VP call request.

The embodiment of the present invention also provides a terminal, including:

A judging unit, a location updating unit, and a sending unit;

The judging unit is used to judge whether it is in a 3G service area, and if so, the location updating unit initiates a 3G location update, and resides the CS domain in the 3G network;

The sending unit is used to send the first VP call request to the network after the CS resides on the 3G network, so that after the network receives the first VP call request, it notifies the called terminal that there is a VP call, and the called terminal receives the VP call request. After the notification, the 3G location is updated, and the CS domain is camped on the 3G network; the subsequent network initiates a second VP call request to the called terminal, so that the terminal performs the VP service according to the VP call.

The embodiment of the present invention also provides a mobile switching center, which can handle both 2G CS services and 3G CS services, including:

Receiving unit, notification unit, location updating unit, calling unit;

The receiving unit is used to receive the second VP call request sent by the calling mobile switching center MSC, and the second VP call request is sent by the calling MSC after receiving the first VP call request of the calling terminal;

The notification unit is configured to notify the called terminal that there is a VP call after receiving the second VP call request through the receiving unit, so that the called terminal passes the location update unit after receiving the notification, or passes the The location updating unit and the HLR perform 3G location updating, and the CS domain resides in the 3G network;

The calling unit is configured to initiate a third VP call request to the called terminal after the called terminal CS domain camps on the 3G network, so that the called terminal performs a VP call according to the second VP call request. business.

The embodiment of the present invention also provides a mobile switching center, the MSC is a 2G MSC for processing 2G CS services, including:

Receiving unit, notification unit, location updating unit, calling unit;

The receiving unit is used to receive the second VP call request sent by the calling mobile switching center MSC, and the second VP call request is sent by the calling MSC after receiving the first VP call request of the calling terminal;

The notification unit is used to notify the called terminal that there is a VP call after receiving the second VP call request through the receiving unit, so that the called terminal performs 3G location update through the 3G MSC and HLR after receiving the notification, Residing the CS domain to the 3G network;

The calling unit is also configured to send a third VP call request to the 3G MSC after the called terminal CS domain resides in the 3G network, so that the 3G MSC sends the third VP call request to the 3G MSC after receiving the third VP call request. The called terminal sends a fourth VP call request, so that the called terminal performs a VP service according to the fourth VP call request.

The above technical solution has the following advantages:

In the embodiment of the present invention, after the network receives the VP call request initiated by the calling terminal, the network notifies the called terminal to update the 3G location, park the CS domain on the 3G network, and then the network transmits the call to the called terminal. Initiate a VP call request, so that the VP service can be performed on the called terminal user whose CS domain resides preferentially on the 2G network.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the descriptions of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only of the present invention. For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a schematic flow chart of a VP calling method according to Embodiment 1 of the present invention;

FIG. 2 is a signaling interaction diagram of network elements in a VP calling method according to Embodiment 1 of the present invention;

FIG. 3 is a signaling interaction diagram of each network element in the VP call method in Embodiment 2 of the present invention;

FIG. 4 is a signaling interaction diagram of each network element in a VP calling method according to Embodiment 3 of the present invention;

FIG. 5 is a schematic flowchart of a method for a calling terminal to make a VP call according to Embodiment 4 of the present invention;

FIG. 6 is a schematic flowchart of a method for a calling terminal to perform a VP call according to Embodiment 5 of the present invention;

FIG. 7 is a schematic flowchart of a method for a calling terminal to make a VP call according to Embodiment 6 of the present invention;

FIG. 8 is a schematic structural diagram of a terminal according to Embodiment 7 of the present invention;

FIG. 9 is a schematic structural diagram of another terminal according to Embodiment 8 of the present invention;

10 is a schematic structural diagram of an MSC according to Embodiment 9 of the present invention;

FIG. 11 is a schematic structural diagram of another MSC according to Embodiment 10 of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below through specific embodiments and related drawings.

Embodiment one

Embodiment 1 of the present invention provides a video phone calling method, referring to FIG. 1 , including the following steps:

S101. Receive a first video telephony (VP) request from a calling terminal;

S102. Notify the called terminal that there is a VP call, so that the called terminal performs 3G location update after receiving the notification, and camps the CS domain on the 3G network;

S103. Initiate a second VP call request to the called terminal, so that the called terminal performs a VP service according to the VP call.

The first VP call request here refers to the VP call request initiated by the calling terminal to the network, and the second VP call request refers to the VP call request initiated by the network to the called terminal, prefixed with "first" and "second" It is used to indicate that VP call requests are initiated by different subjects. The initiation of these two VP call requests follows the standard VP service flow. In the following embodiments, for the convenience of description, "first" and "second" will not be used to strictly distinguish VP call requests. Those skilled in the art can determine the execution subject of the VP call request according to the context, and complete the VP call request in combination with the standard VP call flow.

Referring to Fig. 2, it is a signaling interaction diagram after the above steps are refined in the embodiment of the present invention, assuming that the CS domain of the called terminal resides in 2G at this time, then the processing flow of the complete VP service includes the following steps:

S111. The calling terminal sends a VP call request to the network;

The calling terminal here refers to the terminal that initiates the VP service. It is assumed that the calling terminal is in the 3G network at this time and can initiate a VP service request. The network here refers to the collective name of various related network elements that the operator terminal processes VP services, which can include MSC (Mobile Switch Center, mobile switching center), VLR (Visit Location Register, visit location register), HLR (Home Location Register, belonging location register) and other network elements, these network elements can be based on existing equipment, therefore, they will not be described in detail here.

S112. The network notifies the called terminal that there is a VP call request;

The called terminal here refers to the terminal receiving the VP service. After receiving the VP call request from the calling terminal, the network notifies the called terminal that there is a VP call request.

S113. The network waits for the called terminal to complete the 3G location update;

After notifying the called terminal that there is a VP call request, the network starts to wait for the called terminal to complete the 3G location update;

In this step, a timeout time can also be set by a timer, and if the 3G location update request of the called terminal is not received within the timeout time, the VP call is terminated.

S114. The called terminal sends a 3G location update request to the network;

After receiving the notification from the network in step S112, the called terminal sends a 3G location update request to the network, and subsequently performs 3G location update;

S115. Performing 3G location update, and residing the CS domain in the 3G network;

It should be noted that here it is only required to update the 3G location so that the CS domain resides on the 3G network. Whether the PS (Packet Switch, packet switching) domain resides and on which network it resides is not limited here. The 3G location update process is well known to those skilled in the art, and will not be described in detail here.

S116. The called terminal waits for a VP call request;

In this step, a timer can also be used to set a timeout period. If the VP call request from the network is still not received within the timeout period, step S119 is performed to reset the CS domain to the 2G network.

S117. The network sends a VP call request through 3G

S118. The called terminal starts to perform the VP service according to the VP call;

Both step S117 and step S118 can adopt the existing VP service processing flow, which will not be described in detail here.

S119. Initiate a 2G location update, and re-reside the CS domain to the 3G network.

This step is optional. If the CS domain of the terminal needs to return to the 2G network, it can initiate a 2G location update to reset the CS domain to the 2G network. Of course, if there is no need to camp on the 2G network, the 2G location update may not be performed, and this embodiment of the present invention is not limited here.

In the embodiment of the present invention, after receiving the VP call request initiated by the calling terminal, the network notifies the called terminal to update the 3G location, park the CS domain on the 3G network, and then the network passes the standard VP call process. A VP call request is initiated to the called terminal, so that the VP service can be performed on the called terminal user whose CS domain preferentially resides in the 2G network.

Embodiment two

The embodiment of the present invention provides a video phone call method based on the first embodiment. In the embodiment of the present invention, when the called terminal performs 2G location update, it can register with the network as a special terminal. If it is not registered as a special terminal, then It is an ordinary terminal (existing terminal equipment). The special terminal here refers to an ordinary terminal that cannot support VP services when the CS domain is preferentially camped on the 2G network in the prior art, or in other words, after applying the technical solution of the present invention, it has the ability to preferentially camp on the CS domain. A terminal that supports the VP service capability while remaining on the 2G network; after the network receives the VP call request from the calling terminal, it first judges whether the called terminal is a special terminal based on the information registered by the called terminal on the network. For the terminal, perform VP fallback according to the standard process to end the VP call; if it is a special terminal, continue the subsequent VP process of this solution, and deliver the VP call to the terminal. With this solution, it is possible to avoid initiating VP calls to non-special terminals under 2G, thereby saving paging traffic.

In addition, in the embodiment of the present invention, after the network initiates a VP call to the called terminal, the called terminal can reply a message indicating whether it supports VP calling to the network; if it supports it, the network waits for the terminal to complete the location update after receiving the information Initiate a VP call to perform VP services; if not supported, the network does not make a VP call, and ends the VP call according to the standard-defined process.

It should be noted that the information about whether the called terminal supports VP calls may not depend on the step of "registering with the network whether it is a special terminal", even if the called terminal does not register with the network whether it is a special terminal, the called terminal You can also reply whether you support VP calls. When the called terminal has the software and hardware capabilities to process VP services, and the current state is capable of performing VP services and is in a 3G service area, reply with information about supporting VP calls; otherwise, reply no. Information that supports VP calls. Or, the called terminal can also combine the step of "registering itself as a special terminal with the network" to reply whether it supports VP calling, that is, first register with the network as a special terminal when the 2G location is updated, and then after receiving the VP calling request Reply whether to support VP calls, if the called terminal is a special terminal and is in a 3G service area (3G signal coverage meets the needs of VP services), and the current state can carry out VP services, then reply the information of supporting VP calls; otherwise, reply No Support VP calling.

Referring to Figure 3, it is a signaling interaction diagram of the embodiment of the present invention. In the embodiment of the present invention, in order to describe the solution in more detail, the network in Embodiment 1 is subdivided, specifically including 2G/3G MSC, calling MSC , and HLR, and in practical applications, VLR will also be included. In the embodiment of the present invention, for the convenience of description, the MSC and the VLR are described as a network element entity, which is represented by MSC. A person skilled in the art can select a suitable network element to implement the solution according to the deployment situation of the network element in the actual network in combination with the embodiments of the present invention.

In the embodiment of the present invention, MSC is used for exchanging mobile services and storing user data residing on MSC (usually implemented by VLR, MSC and VLR are usually physically integrated), HLR is mainly used for storing user data, These include user subscription data and the MSC identity where the terminal resides, etc., which are well known to those skilled in the art. Referring to Figure 3, the network element "2G/3G MSC" indicates that the MSC supports both 2G and 3G services; "calling MSC" indicates the MSC that receives the VP call request from the calling terminal. This embodiment mainly describes the situation that a 2G/3G MSC is deployed as an MSC. In addition, the calling MSC and the 2G/3G MSC can also be the same network element device in some cases (for example, both the calling and called terminals are within the coverage of the same MSC), that is, one MSC can simultaneously process 2G/3G services and receive the The VP call request of the calling terminal, the embodiment of the present invention provides the application scenario in most cases, it can be understood that the above-listed shared MSC (the calling MSC and the 2G/3G MSC are the same network element equipment) can also be used The network deployment method or other similar methods are not limited here.

In the embodiment of the present invention, it is also assumed that both the calling terminal and the called terminal have subscribed to the VP service, otherwise the VP service process will be terminated at a certain network element according to the standard definition and the VP service process of normal flow cannot be performed.

In the case that the network includes 2G/3G MSC, calling MSC, and HLR, this solution specifically includes the following steps:

S201. The called terminal initiates a 2G location update, resides in the CS domain on the 2G network, and at the same time registers with the 2G/3GMSC as a special terminal;

When initiating a 2G location update, the terminal first sends a 2G location update request to the 2G/3G MSC, and then completes the location update through the 2G/3G MSC. The process is well known to those skilled in the art, and will not be repeated here.

When the called terminal initiates a 2G location update, it registers as a special terminal with the 2G/3G MSC by carrying a special mark, and the 2G/3G MSC needs to save this information.

S202. The calling MSC receives the VP call request from the calling terminal;

S203. The calling MSC requests the HLR for the routing information of the called terminal according to the VP call request;

S204. The HLR obtains the roaming number from the 2G/3G MSC, and the roaming number includes the routing information of the called terminal (the MSC identifier where the called terminal is located);

S205. The HLR sends the obtained roaming number to the calling MSC;

In the above-mentioned steps, the execution procedures are defined in the standard, and these procedures are well-known technologies by those skilled in the art, and will not be repeated here.

S206. The calling MSC sends a VP call request to the 2G/3G MSC according to the acquired roaming number (including routing information); the VP call request here is also defined in the standard process, and is the same as the "first" in the first embodiment , The "second" VP call request processing method is similar. For the convenience of explanation, it is not strictly distinguished from the VP call request of the calling terminal received by the calling MSC here. Those skilled in the art can according to the standard definition according to the corresponding implementation The main body to complete the VP call request.

Simultaneously, after this step, the 2G/3G MSC can also judge whether it is a special terminal according to the information registered by the called terminal, if yes, then continue to perform step S207, otherwise, end the VP call.

S207. The 2G/3G MSC notifies the called terminal that there is a VP call, and then starts the timer for timing; if the reply from the called terminal in step S208 is not received within the set timeout period, or the The 3G location update request of the terminal terminates the VP call;

Before the 2G/3G MSC notifies the called terminal that there is a VP call, it can judge whether the called terminal is a special terminal, if so, notify the called terminal that there is a VP call, and if not, end the VP service process (not marked in the figure). Because it is not a special terminal that definitely does not support the VP service process described in the present invention, there is no need to issue a VP call request to avoid unnecessary VP call requests;

There are several ways to notify the called terminal that there is a VP call:

1) By way of special SMS

2G/3G MSC sends a short message with special content to the called terminal, informing the called terminal that there is a VP call;

2) Through the SETUP message

The 2G/3G MSC sends paging to the called terminal normally, and after the terminal responds, the 2G/3G MSC sends the SETUP message with VP service to the terminal to notify the called terminal that there is a VP call;

3) Expand the paging message through BSC (Base Station Controller, base station controller)

The 2G/3G MSC sends a paging message to the BSC, and the paging message carries the VP service identifier; then the BSC sends a paging message to the called terminal, and the paging message also carries the VP service identifier; to notify the called terminal The terminal has a VP call;

S208. After receiving the notification, the called terminal replies with information about whether it supports VP calling, so as to inform the 2G/3G MSC whether it supports VP calling;

When the called terminal has the software and hardware capabilities to process VP services, is located in a 3G service area and is able to perform VP services in its current state, it will reply with information that supports VP calls; otherwise, it will reply with information that it does not support VP calls. Since the called terminal may have multiple working states when it is working, and in some states (such as processing other services), the VP service cannot be performed. Therefore, in addition to having software and hardware capabilities and being in a 3G service area, it is necessary to judge the Whether the status can perform VP business.

Depending on how you received the notification, there are several corresponding ways to reply:

1) By way of special SMS

If the SMS notification is received, reply a special SMS to tell 2G/3G MSC whether it supports VP calling;

2) Through the Release Complete message

If the SETUP message is received, the cause value is carried in the Release Complete message, indicating whether the terminal supports VP calls;

3) Extend paging message through BSC

If the BSC extended paging message is received, the VP service identifier is carried when replying to the paging message issued by the 2G/3G MSC, indicating whether the terminal supports VP calling.

In fact, the notification method in step S207 and the method in step S208 in the embodiment of the present invention are not limited to the above three methods, and other self-defined information or existing information can also be used for mutual communication.

S209. After the 2G/3G MSC receives the information returned by the called terminal (within the timeout period set by the timer), it judges whether the called terminal supports VP calling. If the called terminal does not support it, it ends the VP calling according to the standard procedure ( Not shown in the figure); if the called terminal supports it, wait for the called terminal to initiate a 3G location update request (see subsequent step S210);

S210. The called terminal sends a location update request to the 2G/3G MSC 3G, and completes the 3G location update through step S211, and resides the CS domain in the 3G network; wherein, the HLR may or may not participate in the 3G location update process, as shown in Fig. Indicated by a dotted line.

In this step, a timeout time can also be set by a timer. If the VP call request in the step S212 is not received within the timeout time, the VP call is terminated, and the subsequent step S214 is performed to reset the CS domain to 2G network.

In this step, if the called terminal has registered with the 2G/3G MSC as a special terminal, then for this type of terminal, when the 3G location is updated, the authentication and encryption process defined by the standard protocol may not be executed, thereby speeding up the location update and improving The speed of service access reduces the end-to-end connection time of VP services and improves user experience.

It should be noted that, in this embodiment of the present invention, the called terminal may not execute step S208, but directly execute step S210 to initiate a 3G location update; information to determine whether the called terminal supports VP calls, but judges whether it supports VP calls through its registered information, if not, then end the VP call according to the standard process; if it supports, wait for the called terminal to initiate and complete the 3G location update , reside the CS domain to the 3G network. Subsequent steps are the same as the steps when step S208 is executed.

S212.2G/3G MSC initiates a VP call on the 3G network;

When the 2G/3G MSC knows that the 3G location update is completed (the 2G/3G MSC is responsible for processing the 3G location update, so it knows when it is completed), it initiates a VP call to the called terminal on the 3G network.

S213. The called terminal performs the VP service according to the VP call.

The specific execution of step S211, step S212 and step 213 is an existing standard process, and the specific process will not be described in detail here. In this step, for special terminals, the authentication and encryption process may not be performed, so as to improve the service access speed.

S214. The called terminal initiates a 2G network update, and camps the CS domain on the 2G network.

This step is optional. If the CS domain needs to reside on the 2G network again after the VP call ends, initiate a 2G network update to reset the CS domain to the 2G network.

In the embodiment of the present invention, after receiving the VP call request initiated by the calling terminal, the calling MSC notifies the called terminal to update the 3G location, park the CS domain in the 3G network, and then send the CS domain to the 3G network through the 3G network. The called terminal issues a VP call request, thereby realizing the function of performing VP services to users located in the 2G network. In addition, in the embodiment of the present invention, the called terminal can also register as a special terminal with the network. After the network knows that the called terminal is a special terminal, it can accurately issue a VP call request to this type of terminal on the 2G network without having to Normal terminals send VP call requests on the 2G network to avoid unnecessary paging; at the same time, for such special terminals, the authentication and encryption process defined by the standard protocol may not be implemented to improve the service access speed; the called terminal also The 3G location update can be performed directly without replying the information of whether the VP call is supported, so as to improve the service access speed.

Embodiment Three

The embodiment of the present invention provides a method for calling a video phone based on the above-mentioned embodiments. In the embodiment of the present invention, the network 2G MSC and 3G MSC are deployed separately, that is, the network includes 3G MSC, 2G MSC, calling MSC and HLR. The situation of the actual deployment of the MSC in the second is similar, and both the calling MSC and the 3G MSC can be the same MSC.

Referring to FIG. 4, it is a signaling interaction diagram of an embodiment of the present invention, which specifically includes the following steps:

S301. The called terminal initiates a 2G location update, and camps the CS domain on the 2G network;

The 2G location update is completed by the called terminal and the 2G MSC together, and the HLR may participate in the location update process as required. Simultaneously, similar to the situation in Embodiment 2 of the present invention, the called terminal can register as a special terminal with the 2G MSC in this step.

S302. The calling MSC receives the calling terminal VP call request;

S303. The calling MSC requests the routing information of the called terminal from the HLR;

S304. The HLR obtains the roaming number of the called terminal from the 2G MSC, and the number includes routing information;

S305. The HLR sends the roaming number of the called terminal to the calling MSC;

S306. The calling MSC sends a VP call request to the 2G MSC;

Simultaneously, after this step, the 2G MSC can also judge whether it is a special terminal according to the information registered by the called terminal, if yes, then continue to perform step S207, otherwise, end the VP call.

The above steps from S302 to S306 are standard call procedures, which will not be repeated here.

S307.2G MSC notifies the called terminal that there is a VP call request, and performs timer timing;

S308. The called terminal replies with information about whether it supports VP calling;

The specific method used for the notification in step S307 and the specific method used for the reply in step S308 can refer to the relevant part of the description in the second embodiment, and will not be repeated here.

S309.2G MSC receives the reply information from the called terminal within the set timeout period, judges whether the called terminal supports VP calling, if not, ends the VP calling; if it supports, continues to wait for whether it receives the cancellation of location area registration Request (step S311), if received, then continue follow-up process, otherwise, end VP business; If 2G MSC does not receive the information that called terminal replies within the timeout period of setting, also does not receive cancellation location area registration request (step S311), then end VP business;

In the embodiment of the present invention, if the 2G MSC receives the information of supporting VP calling returned by the terminal, it waits for the called terminal to complete the 3G location update. S311) to determine whether the called terminal has completed the 3G location update, and subsequently initiate a VP call request to the 3G MSC.

S310. The called terminal sends a 3G location update request to the 3G MSC, and subsequently completes the 3G location update through the 3G MSC in conjunction with the HLR;

Similar to Embodiment 2, if the called terminal registers with the 3G MSC as a special terminal when the 3G location is updated, then for this type of terminal, when the 3G location is updated, the authentication and encryption process defined by the standard protocol may not be executed to improve service Access speed.

At the same time, in this step, the called terminal can also set a timeout time through a timer. If the VP call request in step S316 is not received within the timeout time, the VP call is terminated, and the subsequent step S318 is performed to reset the CS domain. Residing on a 2G network.

S311. The HLR sends a request for deregistration of the location area to the 2G MSC, and the 2G MSC deregisters the registration of the location area according to the request; this step is defined by the standard and will not be repeated here.

S312.2G MSC requests called terminal routing information from HLR;

After step S311 is executed, the 2G MSC knows that the called terminal has completed the 3G location update process, and can initiate a VP service to the called terminal. Find the 3G MSC where the called terminal resides by re-initiating the process of obtaining the called terminal routing information from the HLR, so as to complete the subsequent VP service process.

The process of the 2G MSC requesting the called terminal routing information from the HLR and the subsequent S313 to S317 are all processes defined by the standard protocol, and will not be repeated here.

S313. The HLR obtains the roaming number of the called terminal from the 3G MSC, and the number contains routing information;

S314. The HLR sends the roaming number of the called terminal to the 2G MSC;

S315.2G MSC sends a VP call request to 3G MSC according to the roaming number;

Because the roaming number contains routing information, it can specifically send a VP call request to the 3G MSC according to the routing information in the roaming number.

S316.3G MSC notifies the called terminal that there is a VP call request;

S317. After receiving the VP call request, the called terminal performs the VP call according to the standard procedure;

If the called terminal registers with the 3G MSC as a special terminal when the 3G location is updated, then for this type of terminal, when performing VP services, the authentication and encryption process defined by the standard protocol may not be executed to improve the service access speed.

S318. The called terminal performs a 2G location update, and allows the CS domain to reside on the 2G network again.

In another embodiment of the present invention, after the called terminal replies with the information of whether to support VP calling (S308), if the 2G MSC does not receive the information of the reply within the timeout period, but receives the request for canceling location area registration (S311 ), also can continue VP service, if neither receive the information (S308) that the called terminal replies whether to support VP calling within the timeout period, also do not receive the deregistration location area registration request (S311), then end VP service. The advantage of this design is: when the called terminal replies the information of whether it supports VP calling (S308), the replied information may be lost, and in this case, the VP calling can be continued as long as the cancellation location area registration request (S311) is received process. However, this solution does not end the VP service immediately because the information returned by the called terminal is not received, but judges whether the request for canceling the location area registration is received within the timeout period. Therefore, the above-mentioned situation of VP service termination can be avoided.

Through the embodiment of the present invention, it is possible to perform VP service on a called terminal located in a 2G network on a network based on a 2G MSC and a network where a 3G MSC is not located on one network element.

The main difference between this embodiment and Embodiment 2 is that it is necessary to solve the problem of how the 2G MSC connects the VP call to the 3G MSC after the called terminal resides on the 3G MSC from the 2G MSC due to location update during the VP service call process. question. In this embodiment, the 2G MSC adopts the method of performing step S312 after step S311 to find the 3G MSC where the called terminal resides again, so as to realize the call connection of the subsequent VP service. The advantage of this method is that it only needs to modify one network element of the 2G MSC. The standard protocol also defines another method of "roaming recall" to achieve the same purpose, but it needs HLR, calling MSC and 2G MSC to cooperate and modify to support the "roaming recall" function. There are many network elements to be modified, and the existing network deployment more difficult. The specific implementation scheme of "roaming recall" will not be repeated here. The present invention can also use this "roaming recall" method to realize the transfer of VP calls from 2G MSC to 3G MSC.

Embodiment Four

The embodiment of the present invention provides a VP call method, which is applied to the calling terminal. Assuming that the CS domain of the calling terminal is preferentially camped on the 2G network, see FIG. 5, the method includes the following steps:

S401. Determine whether it is in a 3G service area, if yes, execute step S402, if no, do not perform VP business;

Whether the calling terminal is in the 3G service area can be judged by periodic detection or constant detection of the strength of the 3G signal. Only when the signal strength meets a certain threshold, it is considered to be in the 3G service area and the VP service can be performed; otherwise, the VP service cannot be performed. VP business.

S402. Initiating a 3G location update, and residing the CS domain on the 3G network;

The specific location update process is a process defined by the standard, and will not be repeated here;

S403. Sending a VP call request to the network, so that the network processes the VP service according to the VP call request;

Wherein, when the network processes the VP service, if the CS domain of the called terminal resides in the 3G network, the processing can be performed directly according to the normal process; otherwise, if the CS domain of the called terminal resides in the 2G network, the method can be implemented through the present invention. The methods provided in Examples 1, 2, and 3 are processed so that the calling terminal and the called terminal can mutually perform VP services.

S404. After the VP service ends, the terminal initiates a 2G location update, and re-residents the CS domain to the 2G network.

This step is optional. If it is necessary to implement the original strategy of the CS domain residing on the 2G network, this step can be performed; otherwise, the CS domain can continue to be residing on the 3G network.

In step S402 of the embodiment of the present invention, as one of the optimization measures of the above process, when the terminal initiates a location update, it instructs the network to use the Follow on method (that is, tells the network not to disconnect the connection after the location update is completed, and the terminal will also initiate other business processes , refer to the standard definition), and then initiate the VP service, which can shorten the VP service establishment delay.

Secondly, in the embodiment of the present invention, the calling terminal may also register with the network as a special terminal when the 2G location is updated, that is, a terminal capable of initiating a VP call from the 2G network. When the network knows that the calling terminal is a special terminal, the location update and VP services initiated by such terminals are not authenticated, encrypted and integrity checked, which can shorten the VP service establishment delay.

Through the embodiment of the present invention, the terminal whose CS originally resides in the 2G network can perform the VP service after actively initiating a 3G location update.

Embodiment five

The embodiment of the present invention provides a VP call method, which is applied to the calling terminal. It is assumed that the CS domain of the calling terminal is preferentially camped on the 2G network. Referring to FIG. 6, the method includes the following steps:

S501. Determine whether it is in the 3G server, if yes, execute step S502, if not, do not perform VP service;

For the method for the calling terminal to determine whether it is in the 3G service area, please refer to the relevant description in step S401, which will not be repeated here.

S502. The calling terminal directly initiates a VP call to the calling MSC on the 3G, so that the calling MSC initiates a 3G location update process after receiving the VP call, and camps the CS domain on the 3G network;

In this case, the calling terminal does not initiate a 3G location update, and the process of directly initiating a VP call on 3G is similar to the case of an emergency call; at the same time, the calling MSC finds that there is no user data of this user after receiving the VP call from the calling terminal , the calling MSC can actively trigger a location update process to obtain user data from the HLR, and then perform subsequent VP service processes.

S503. After the VP service ends, the terminal initiates a 2G location update, and re-residents the CS domain to the 2G network.

In the embodiment of the present invention, the called terminal does not initiate the location update, but the calling terminal initiates the location update.

Implementation six

The embodiment of the present invention provides a VP calling method, which is applied to the calling terminal. It is assumed that the CS domain of the calling terminal is preferentially camped on the 2G network. Referring to FIG. 7, the method includes the following steps:

S601. Determine whether it is in the 3G server, if it is, execute step S502, if not, do not perform the VP service;

S602. The calling terminal directly initiates a VP call to the calling MSC on 3G, so that the calling MSC obtains the user data from the HLR by using the process of recovering user data;

In this step, the calling terminal does not need to initiate a location update first to shorten the time delay; since the calling MSC does not have the data of the calling terminal user, the MSC can adopt the process of recovering the user data to obtain the user data from the HLR, wherein, "Recover "User Data Process" is also a standard process, so I won't repeat it here.

S603. After the VP service ends, determine whether the 2G location area has changed from before the VP service. If there is a change, initiate a location update process on 2G, and reside in the CS domain on the 2G network; otherwise, it is not necessary to initiate a location update process on 2G. , while directly residing on 2G.

In the embodiment of the present invention, the calling MSC obtains the user data from the HLR by adopting the process of recovering the user data, and does not need to update the 3G location. At the same time, after the VP service ends, usually the location area where the user is located may be the same as the location area before the VP service in most cases. At this time, after the VP service ends, there is no need to update the 3G location. In most cases, two 3G location update processes can be saved, which can reduce the caller connection delay and reduce the time when the mobile phone is in an unreachable state (during the location update process, the mobile phone can neither make nor answer calls, in a state of being unavailable for business).

Embodiment seven

Referring to FIG. 8 , an embodiment of the present invention provides a terminal 80 based on the above embodiments, including:

A receiving unit 81, a location updating unit 82, and a service executing unit 83;

The receiving unit is used to receive a notification that the called terminal has a video phone VP call, and the notification is sent by the network after receiving the first VP call request of the calling terminal;

The location update unit is used for the receiving unit to update the 3G location after receiving the notification, and to reside the CS domain in the 3G network;

The receiving unit is further configured to receive a second VP call request sent by the network after the CS domain resides in the 3G network;

The service execution unit is configured to perform a VP service according to the second VP call request.

The embodiment of the present invention also includes: a registration unit 84, configured to register as a special terminal in the network when the 2G location is updated, so that after the network receives the first VP call request from the calling terminal, it can judge according to the information registered in the network Whether the called terminal is a special terminal, if not, end the VP call, if yes, notify the called terminal that there is a VP call.

The embodiment of the present invention also includes: a reply unit 85, configured to reply when the called terminal has the software and hardware capabilities to process VP services, is located in a 3G service area, and can perform VP services in its current state after receiving the notification. Support the information of VP call; otherwise reply the information that does not support VP call; make the network judge whether the terminal supports VP call according to the information replied, if yes, then wait for the called terminal to complete the 3G location update process, and then initiate the VP call to proceed VP service; if not supported, end the VP call.

For specific processing procedures of each unit, reference may be made to the above-mentioned related embodiments, and details are not repeated here.

Through the embodiment of the present invention, the VP service to the terminal located in the 2G network can be realized. Each of the above units can be implemented based on various hardware of the existing terminal (for example, adding corresponding program codes to the hardware), and the specific process is well known to those skilled in the art, and will not be repeated here.

Embodiment Eight

Referring to FIG. 9 , an embodiment of the present invention provides a terminal 90 based on the above embodiments, including:

Judging unit 91, location updating unit 92, sending unit 93;

The judging unit is used to judge whether it is in a 3G service area, if not, the location updating unit initiates a 3G location update, and resides the CS domain in the 3G network;

The sending unit is used to send the first VP call request to the network after the CS resides on the 3G network, so that after the network receives the first VP call request, it notifies the called terminal that there is a VP call, and the called terminal receives the VP call request. After the notification, the 3G location is updated, and the CS domain is camped on the 3G network; the subsequent network initiates a second VP call request to the called terminal, so that the terminal performs the VP service according to the VP call.

For specific processing procedures of each unit, reference may be made to the above-mentioned related embodiments, and details are not repeated here.

Through the embodiment of the present invention, it is possible to use a terminal located in a 2G network to initiate a VP service. Each of the above units can be implemented based on various hardware of the existing terminal (for example, adding corresponding program codes to the hardware), and the specific process is well known to those skilled in the art, and will not be repeated here.

Embodiment nine

Referring to Fig. 10, the embodiment of the present invention provides a kind of MSC 10, and this MSC can handle the CS business of 2G, also can handle the CS business of 3G, and described MSC comprises:

A receiving unit 101, a notification unit 102, a location updating unit 103, and a calling unit 104;

The receiving unit is used to receive the second VP call request sent by the calling mobile switching center MSC, and the second VP call request is sent by the calling MSC after receiving the first VP call request of the calling terminal;

The notification unit is configured to notify the called terminal that there is a VP call after receiving the second VP call request through the receiving unit, so that the called terminal passes the location update unit after receiving the notification, or passes the The location updating unit and the HLR perform 3G location updating, and the CS domain resides in the 3G network;

The calling unit is configured to initiate a third VP call request to the called terminal after the called terminal CS domain camps on the 3G network, so that the called terminal performs a VP call according to the second VP call request. business.

The receiving unit is further configured to receive information about whether a VP call is supported returned by the terminal after the notification unit notifies the called terminal that there is a VP call;

The MSC also includes:

The judging processing unit 105 is configured to judge whether the called terminal supports VP calling according to the returned information, and if so, wait for the called terminal to complete the 3G location update process, and subsequently initiate the second VP calling request to perform VP services; If not supported, the VP call is ended.

The MSC also includes:

A registration unit 106, configured to complete the registration of the called terminal when the called terminal performs 2G location update, so that the called terminal is registered as a special terminal;

The second judgment processing unit 107 is configured to judge whether the called terminal is a special terminal according to the registered information of the called terminal after the receiving unit receives the second VP call request, and if so, through the notification unit Notify the called terminal that there is a VP call request, otherwise, end the VP call.

The MSC in the embodiment of the present invention can be based on the 2G/3G MSC embodiment in the second embodiment, and its specific processing can refer to the description in the above embodiment, and will not be repeated here.

Embodiment ten

Referring to Fig. 11, the embodiment of the present invention provides a mobile switching center MSC 11, the MSC is a 2GMSC for processing 2G CS services, including:

A receiving unit 111, a notification unit 112, a location updating unit 113, and a calling unit 114;

The receiving unit is used to receive the second VP call request sent by the calling mobile switching center MSC, and the second VP call request is sent by the calling MSC after receiving the first VP call request of the calling terminal;

The notification unit is used to notify the called terminal that there is a VP call after receiving the second VP call request through the receiving unit, so that the called terminal performs 3G location update through the 3G MSC and HLR after receiving the notification, Residing the CS domain to the 3G network;

The calling unit is also configured to send a third VP call request to the 3G MSC after the called terminal CS domain resides in the 3G network, so that the 3G MSC sends the third VP call request to the 3G MSC after receiving the third VP call request. The called terminal sends a fourth VP call request, so that the called terminal performs a VP service according to the fourth VP call request.

The receiving unit is further configured to receive the location area deregistration request sent by the HLR after the called terminal completes the 3G location update;

The location update unit is further configured to cancel the location area registration after the receiving unit receives the location area registration cancellation request;

The calling unit is further configured to request the HLR for routing information of the called terminal after the location area registration is canceled, so that the HLR obtains the roaming number of the called terminal from the 3G MSC, and the roaming number contains all Describe the routing information of the called terminal;

The receiving unit is further configured to receive the roaming number of the called terminal sent by the HLR after the HLR acquires the roaming number of the called terminal;

The calling unit is further configured to, after the receiving unit receives the roaming number of the called terminal, send a third VP call request to the 3G MSC according to the routing information in the roaming number.

Embodiments of the invention also include:

The registration unit 115 is configured to complete the registration of the called terminal when the called terminal performs 2G location update, so that the called terminal is registered as a special terminal;

The judgment processing unit 116 is configured to judge whether the called terminal is a special terminal according to the registered information of the called terminal after the receiving unit receives the second VP call request, and if so, notify the called terminal through the notification unit The called terminal has a VP call request, otherwise, end the VP call.

The MSC in the embodiment of the present invention may be based on the 2G MSC embodiment in the third embodiment, and may also include processing. For specific processing, please refer to the description in the above embodiment, which will not be repeated here.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented through computer programs to instruct related hardware, and the programs can be stored in a computer-readable storage medium. During execution, it may include the processes of the embodiments of the above-mentioned methods. Wherein, the storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM) or a random access memory (Random Access Memory, RAM), etc.

The above-listed preferred embodiments have further described the purpose, technical solutions and advantages of the present invention in detail. It should be understood that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included within the protection scope of the present invention.

Claims (25)

1. A video telephony call method, comprising the steps of:

receiving a first Video Phone (VP) call request of a calling terminal;

informing a called terminal of VP calling, so that the called terminal carries out 3G location updating after receiving the notification, and residing a CS domain in a 3G network;

and initiating a second VP call request to the called terminal, so that the called terminal carries out VP service according to the second VP call request.

2. The method of claim 1, wherein after receiving the video telephony first VP call request of the calling terminal, further comprising:

judging whether the called terminal is a special terminal according to the information registered in the network when the called terminal is updated at the 2G position, if not, finishing the VP call, if so, informing the called terminal that the VP call exists, so that the called terminal carries out the 3G position update after receiving the notification, and residing the CS domain in the 3G network; the special terminal refers to a terminal with the capability of supporting the VP service in the case that the CS domain preferentially resides in the 2G network.

3. The method of claim 1, wherein after notifying the called terminal of the VP call, further comprising;

receiving information whether the VP call is supported or not replied by the called terminal;

judging whether the terminal supports the VP call according to the replied information, if so, waiting for the called terminal to finish the 3G position updating process, and subsequently initiating the second VP call request to carry out the VP service; if not, the VP call is ended.

4. The method of claim 3, wherein after notifying the called terminal of the VP call, further comprising:

starting a timer for timing, if the information whether the called terminal replies to support the VP call is not received within the set overtime, or the 3G position updating request of the called terminal is not received, terminating the VP service; the 3G location updating request is initiated by the called terminal when the 3G location updating process begins.

5. The method of claim 1, wherein the notifying the called terminal of the VP call comprises:

sending a short message with special content to the called terminal to inform the called terminal of VP calling;

or,

sending a page to a called terminal, and sending a SETUP message with a VP service identifier to the called terminal after the called terminal responds to inform that the called terminal has a VP call;

or,

sending a paging message to a base station controller BSC, wherein the paging message carries a VP service identifier; then BSC will send the paging message to the called terminal, the paging message also carries VP service identification; to inform the called terminal of the VP call.

6. A video telephony call method, comprising the steps of:

receiving a notification that a called terminal has a video phone VP call, wherein the notification is sent after a first VP call request of a calling terminal is received by a network;

updating the 3G position, and residing the CS domain to the 3G network;

and receiving a second VP call request sent by the network, and carrying out VP service according to the second VP call request.

7. The method of claim 6, wherein prior to receiving the notification that the called terminal has a video telephony (VP) call, further comprising:

registering the called terminal as a special terminal in the network during 2G position updating, so that the network judges whether the called terminal is the special terminal according to the information registered in the network after receiving the first VP call request of the calling terminal, if not, finishing the VP call, and if so, informing the called terminal of the VP call; the special terminal refers to a terminal with the capability of supporting the VP service in the case that the CS domain preferentially resides in the 2G network.

8. The method of claim 6, wherein after receiving the notification that the called terminal has a video telephony (VP) call, further comprising:

replying information whether the VP call is supported or not to the network; the network judges whether the terminal supports the VP call according to the replied information, if so, the network waits for the called terminal to finish the 3G position updating process, and then initiates the VP call to carry out the VP service; if not, the VP call is ended.

9. The method of claim 8, further comprising:

when the called terminal has the software and hardware capability of processing the VP service, is positioned in the 3G service area and can carry out the VP service in the current state, replying the information supporting the VP call; otherwise, the information that the VP call is not supported is replied.

10. A video telephony call method, comprising the steps of:

judging whether the CS domain is in a 3G service area, if so, initiating 3G location update, and residing the CS domain in a 3G network;

sending a first VP call request to a network, so that the network informs a called terminal of a VP call after receiving the first VP call request, and the called terminal carries out 3G location update after receiving the notification and resides a CS domain in the 3G network; and the subsequent network initiates a second VP call request to the called terminal, so that the terminal carries out VP service according to the VP call.

11. A video telephony call system, comprising:

the system comprises a 2G/3G mobile switching center MSC, a calling mobile switching center MSC and a location home register HLR, wherein the 2G/3G MSC indicates that the MSC can process the CS service of 2G and the CS service of 3G;

the calling MSC is used for receiving a first VP call request of a calling terminal and sending a second VP call request to the 2G/3G MSC;

the 2G/3G MSC is used for notifying a called terminal of VP call after receiving the second VP call request, so that the called terminal carries out 3G location update through the 2G/3G MSC or through the 2G/3G MSC and the HLR after receiving the notification, and a CS domain is resided in a 3G network;

the 2G/3G MSC is further configured to initiate a third VP call request to the called terminal after the CS domain of the called terminal resides in the 3G network, so that the called terminal performs VP service according to the second VP call request.

12. The method of claim 11, wherein the 2G/3G MSC is further to:

after informing the called terminal of VP call, receiving the information whether the called terminal replies supports VP call;

judging whether the called terminal supports the VP call according to the replied information, if so, waiting for the called terminal to finish the 3G position updating process, and subsequently initiating the second VP call request to carry out the VP service; if not, the VP call is ended.

13. A video telephony call system, comprising:

2G mobile switching center MSC, 3G mobile switching center MSC, calling mobile switching center MSC and location home register HLR;

the calling MSC is used for receiving a first VP call request of a calling terminal and sending a second VP call request to the 2G MSC;

the 2G MSC is used for notifying a called terminal of VP calling after receiving the second VP calling request, so that the called terminal carries out 3G location updating through the 3G MSC and the HLR after receiving the notification, and a CS domain is resided in a 3G network;

the 2G MSC is further configured to send a third VP call request to the 3G MSC after the CS domain of the called terminal resides in the 3G network, and the 3G MSC sends a fourth VP call request to the called terminal after receiving the third VP call request, so that the called terminal performs VP service according to the fourth VP call request.

14. The system of claim 13, wherein the 2G MSC is further to:

after informing the called terminal of VP call, receiving the information whether the called terminal replies supports VP call;

judging whether the called terminal supports the VP call according to the replied information, if so, waiting for the called terminal to finish the 3G position updating process, and subsequently initiating the second VP call request to carry out the VP service; if not, the VP call is ended.

15. The system of claim 13, wherein the 2G MSC is further to:

after the called terminal completes the 3G position updating, the position area registration is cancelled according to the received cancellation position area registration request sent by the HLR;

requesting routing information of a called terminal from the HLR, so that the HLR acquires a roaming number of the called terminal from the 3G MSC, wherein the roaming number contains the routing information of the called terminal;

and receiving the called terminal roaming number sent by the HLR, and sending a third VP call request to the 3G MSC according to the routing information in the roaming number.

16. A terminal, comprising:

the system comprises a receiving unit, a position updating unit and a service execution unit;

the receiving unit is used for receiving a notification that a called terminal has a video telephone VP call, and the notification is sent after a first VP call request of a calling terminal is received by a network;

the location updating unit is used for the receiving unit to update the 3G location after receiving the notification and reside the CS domain in the 3G network;

the receiving unit is further configured to receive a second VP call request sent by the network after the CS domain resides in the 3G network;

the service execution unit is used for carrying out VP service according to the second VP call request.

17. The terminal of claim 16, further comprising:

and the registration unit is used for registering as a special terminal in a network when the 2G position is updated, so that the network judges whether the called terminal is the special terminal according to the information registered in the network after receiving the first VP call request of the calling terminal, if not, the VP call is ended, and if so, the called terminal is informed of the VP call.

18. The terminal of claim 16, further comprising:

a reply unit, configured to reply the information supporting the VP call when the called terminal has the software and hardware capability of processing the VP service, is located in the 3G service area, and is in a current state capable of performing the VP service after receiving the notification; otherwise, replying the information that VP call is not supported; the network judges whether the terminal supports the VP call according to the replied information, if so, the network waits for the called terminal to finish the 3G position updating process, and then initiates the VP call to carry out the VP service; if not, the VP call is ended.

19. A terminal, comprising:

the device comprises a judging unit, a position updating unit and a sending unit;

the judging unit is used for judging whether the CS domain is in a 3G service area or not, if so, the position updating unit initiates 3G position updating and resides the CS domain in a 3G network;

the sending unit is used for sending a first VP call request to the network after the CS resides in the 3G network, so that the network informs the called terminal of the VP call after receiving the first VP call request, and the called terminal updates the 3G position after receiving the inform and resides the CS domain in the 3G network; and the subsequent network initiates a second VP call request to the called terminal, so that the terminal carries out VP service according to the VP call.

20. A mobile switching center, MSC, capable of handling both 2G and 3G CS services, the MSC comprising:

the system comprises a receiving unit, a notification unit, a position updating unit and a calling unit;

the receiving unit is used for receiving a second VP call request sent by a calling Mobile Switching Center (MSC), and the second VP call request is sent after the calling MSC receives a first VP call request of a calling terminal;

the notifying unit is configured to notify the called terminal that there is a VP call after receiving the second VP call request through the receiving unit, so that the called terminal performs 3G location update through the location updating unit after receiving the notification, and resides the CS domain in the 3G network;

the call unit is configured to initiate a third VP call request to the called terminal after the CS domain of the called terminal resides in the 3G network, so that the called terminal performs VP services according to the second VP call request.

21. The MSC of claim 20, wherein:

the receiving unit is further configured to receive information whether VP call is supported or not replied by the terminal after the notification unit notifies the called terminal that there is a VP call;

the MSC further comprises:

a judging and processing unit, configured to judge whether the called terminal supports the VP call according to the replied information, and if so, wait for the called terminal to complete a 3G location update procedure, and subsequently initiate the second VP call request through the calling unit to perform the VP service; if not, the VP call is ended.

22. The MSC of claim 20, further comprising:

the registration unit is used for finishing registration of the called terminal when the called terminal carries out 2G position updating so as to ensure that the called terminal is registered as a special terminal;

and a second judgment processing unit, configured to, after the receiving unit receives the second VP call request, judge whether the called terminal is a special terminal according to the information that the called terminal is registered, if so, notify the called terminal of the VP call request through the notification unit, and otherwise, end the VP call.

23. A mobile switching center, MSC, wherein the MSC is a 2G MSC, and is configured to handle CS services of 2G, and the MSC includes:

the system comprises a receiving unit, a notification unit, a position updating unit and a calling unit;

the receiving unit is used for receiving a second VP call request sent by a calling Mobile Switching Center (MSC), and the second VP call request is sent after the calling MSC receives a first VP call request of a calling terminal;

the notifying unit is configured to notify the called terminal that there is a VP call after receiving the second VP call request through the receiving unit, so that the called terminal performs 3G location update through the 3G MSC and the HLR after receiving the notification, and resides the CS domain in the 3G network;

the calling unit is further configured to send a third VP call request to the 3GMSC after the CS domain of the called terminal resides in the 3G network, so that the 3G MSC sends a fourth VP call request to the called terminal after receiving the third VP call request, so that the called terminal performs VP service according to the fourth VP call request.

24. The MSC of claim 23, wherein:

the receiving unit is further configured to receive a location area deregistration request sent by the HLR after the called terminal completes the 3G location update;

the location updating unit is further configured to deregister the location area after the receiving unit receives the deregistering location area registration request;

the calling unit is also used for requesting routing information of a called terminal from the HLR after the registration of a logout position area, so that the HLR acquires a roaming number of the called terminal from the 3G MSC, wherein the roaming number contains the routing information of the called terminal;

the receiving unit is further configured to receive the called terminal roaming number sent by the HLR after the HLR acquires the called terminal roaming number;

and the calling unit is also used for sending a third VP calling request to the 3G MSC according to the routing information in the roaming number after the receiving unit receives the roaming number of the called terminal.

25. The MSC of claim 23, further comprising:

the registration unit is used for finishing registration of the called terminal when the called terminal carries out 2G position updating so as to ensure that the called terminal is registered as a special terminal;

and the judging and processing unit is used for judging whether the called terminal is a special terminal according to the registered information of the called terminal after the receiving unit receives the second VP call request, if so, the informing unit informs the called terminal that the VP call request exists, and otherwise, the VP call is ended.

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