CN1311694C - Evolution system and method of public switched telephone network - Google Patents

Abstract

The invention relates to the communication field, and discloses a public telephone switching network evolution system and its method, so that the existing equipment and network resources can be reused as much as possible, so that the cost is low, the reuse rate of the switch and its software is high, and the engineering implementation The difficulty is relatively reduced. The core of this public switched telephone network evolution system and its method is that, firstly, the switch of the tandem office is transformed into a service switching point, so that it has a service switching function, and can trigger calls to corresponding service control points according to different conditions. secondly, there is no need to upgrade the end office switch, it only needs to use its call forwarding function to forward all services to the service exchange point in the tandem office through data configuration; thirdly, the billing center only needs Click Get Service Information for Billing.

Description

Public switched telephone network evolution system and method

technical field

The invention relates to the communication field, in particular to the evolution technology of the public telephone switching network.

Background technique

In the current telecommunications business network, the public switched telephone network (Public Switched Telephone Network, referred to as "PSTN") based on bearer, control integration and circuit switching provides most of the fixed voice and other telecommunications services Telecom users and operating income. The advantage of the PSTN network is that it has a huge network infrastructure and a huge number of users; the voice quality of service (Quality of Service, referred to as "QoS") is good; and the business is rich.

However, with the integration trend of the industry, the telephone network, computer network, and cable TV network tend to be integrated, and the pressure on the network is increasing. The network is faced with increasing load and diversification of service requirements. Telecom operators must provide more and more multimedia services to attract users. Under this development background, the next generation network based on softswitch technology ( Next Generation Network, referred to as "NGN") came into being. NGN is a milestone in the history of telecommunications. It belongs to a comprehensive and open network architecture and provides services such as voice, data and multimedia. NGN can integrate communication, information, e-commerce and transaction services on a unified packet network to meet diversified and personalized business needs. Compared with PSTN networks, packet networks have more advantages: more effective use of bandwidth and equipment ; Reduce the cost of voice transmission; can provide innovative services combining voice and data.

Whether it is NGN or the third generation mobile communication (The Third Generation, referred to as "3G") network, in order to achieve the greatest degree of service scalability, on the basis of packet technology, strive to separate business logic processing and media processing, That is, exchange and control are separated. However, the network must adopt an evolutionary model: from the perspective of telecom operators, they must protect their telecom assets and existing telecom services to the greatest extent; from the perspective of users, they hope to protect their investment and usage habits On the basis of the Internet, add some broadband services with simple operation and low price. Therefore, how NGN or 3G inherits the services of the original PSTN network and how to fully reuse the network resources of the PSTN must be studied. There are several evolutionary models that are generally popular:

(1) Integrated model evolution

In the integrated model, the key functional components of NGN, such as multi-service access, broadband switching, call control, service generation, etc., will be integrated into the integrated service switch, and the current circuit switching system will be guaranteed by a single switch architecture. The network evolves into the multi-service platform of NGN.

(2) Distributed Model Evolution

The next generation network is composed of separate components: call/session control module, application server (Application Server, "AS" for short), gateway, switch and router, etc.

These two modes start from the perspective of implementation. The second mode is currently widely recognized in the industry. However, the description of these two modes lacks the consideration of the structure of the current PSTN network. In order to reduce the complexity of the network, the PSTN network To increase the utilization rate of the network, a multi-level networking mode is generally adopted, which can be basically divided into two types: Local Exchange ("LE" for short) and Tandem Exchange ("TE" for short). LE and The main equipment in the TE is a traditional program-controlled switch. The program-controlled switch of the LE is directly connected to the subscriber line, but the TE is not connected to the subscriber line. As shown in Figure 1: the PSTN network consists of a billing center 10, a service control point 11, Tandem office 12, tandem office 13, end office 14, end office 15, end office 16, end office 17, end office 18, and end office 19. End Office 14, End Office 15, End Office 16, End Office 17, End Office 18, and End Office 19 are respectively connected to two upper-level tandem offices 12 and 13 to provide users with C5 services, that is, for access users services directly related to user terminals; the interconnection between the tandem office 12 and the tandem office 13 provides service aggregation and C4 services, namely relay and aggregation services; billing center 10 (Billing Cneter) needs to follow The tandem office 12 and the tandem office 13 are connected to all end offices to obtain sufficient charging information; the service control point 11 (Service Control Point, referred to as "SCP") can be connected to the tandem office 12 and the tandem office 13, It can also be directly connected to the end office. It should be noted that SCP refers to the control point that supports advanced telephone services and intelligent network communication protocol services in the world, that is, the service control point of the No. 7 signaling system, defined in the SCP intelligent network The control element, its function is generally a database that determines how calls are processed, and provides control logic for intelligent services.

One of the most commonly used evolution methods is the separated evolution mode.

The basic network diagram after the completion of this evolution mode is shown in Figure 2, by the billing center 20, the service control point 21, the control entity 22, the media gateway (Media Gateway, referred to as "MG") 23, the media gateway 24, the media gateway 25. The media gateway 26, the media gateway 27, the media gateway 28, and the media gateway 29 are composed.

Among them, the media gateway 25, the media gateway 26, the media gateway 27, the media gateway 28, and the media gateway 29 are respectively connected with two upper-level media gateways 23 and 24, and provide users with C5 services or other services directly related to user terminals. .

The media gateway 23 and the media gateway 24 replace the functions of the tandem office 12 and the tandem office 13 in FIG. 1 .

It should be noted that the control entity 22 (Call Server) is a device in a logical sense, and is sometimes referred to as a media gateway controller (Media Gateway Control, "MGC" for short), media gateway 23, media gateway 24, media gateway 25, The actions of the media gateway 26, the media gateway 27, the media gateway 28, and the media gateway 29 are all executed according to the command of the control entity 22, and the control entity 22 mainly pays attention to the C4 business of the media gateway 23 and the media gateway 24, and pays attention to the media gateway 25, the media gateway 25, and the media gateway 24. The gateway 26, the media gateway 27, the media gateway 28, and the media gateway 29 are mainly C5 services. In the early stage of network evolution, the control entity 22 may be divided into two according to different services of interest. During the network evolution process, the two control entities can be merged into one to control multiple types of media gateways.

The charging center 20 needs the control entity 22 to be connected to all media gateways to obtain sufficient charging information.

The service control point 21 only needs to be connected with the control entity 22 in this network to provide the control logic of the intelligent service.

In this evolution mode, the evolution mode of LE and TE is adopted separately. For LE, the control function and switching function of the LE switch are separated, that is, the traditional program-controlled switch in all end offices in Figure 1 is evolved into a simple switching node. That is, it becomes a media gateway, and all actions are executed according to the commands of the separated control entity 22, and the interface for intelligent services is also completed by the control entity; it is basically the same for TE, and the traditional The program-controlled switch has evolved into a pure switching node, that is, a media gateway, but the separated control entity mainly focuses on C4 services.

In this evolution mode, the traditional program-controlled switches of TE and LE need to be upgraded to become a media gateway that only completes circuit switching and forwarding functions based on the above commands. As for the uplink media interface, the traditional time division can be retained. The multiplexing (Time Division Multiplexing, referred to as "TDM") interface can also be directly evolved into a gateway supporting a packet interface.

Although the above-mentioned method achieves the separation of control and switching in one step, and adopts Call Server as a unified business control entity, it provides a very good platform for future expansion. However, if the current network situation is considered, the following disadvantages appear :

1) This evolution mode requires all traditional program-controlled switches to be upgraded, and the cost is relatively high;

2) Many traditional program-controlled switches cannot be upgraded due to various historical reasons such as the manufacturer and the technology used, so they must be replaced directly, and the reuse rate is not high;

3) Most of the software in traditional program-controlled switches are no longer useful.

All in all, this solution requires telecom operators to immediately replace all the program-controlled switch node equipment on the previous PSTN network with new equipment, which is equivalent to establishing a new service network, which will have a great impact on the existing network of telecom operators, and the risk is also the same big.

Figure 3 shows another evolution mode—the evolution mode of the intelligent network. The basic network charging center 30, service control point 31, service exchange point 32, service exchange point 33, service exchange point 34, service exchange point 35, service exchange point 36, service exchange point 37, service Switching points 38 are formed.

Among them, the business switching point 34, the business switching point 35, the business switching point 36, the business switching point 37, and the business switching point 38 are respectively connected with the two upper-level business switching points 32 and 33 to provide users with C5 services or other, Services directly related to user terminals.

The service switching point 32 and the service switching point 33 have replaced the functions of the tandem office 12 and the tandem office 13 in FIG. 1 .

The billing center 30 needs to be connected to all service switching points to obtain sufficient billing information.

In this network, the service control point 31 can be connected with the upper-level service exchange point 32 and the service exchange point 33, and can also be connected with the lower-level service exchange point 34, service exchange point 35, service exchange point 36, service exchange point 37, and service exchange point 38, which can also provide the control logic of intelligent services.

In this evolution mode, LE and TE follow the evolution mode of the intelligent network. This evolution does not adopt the direct and complete separation of control and switching described in Technical Solution 1, but uses the traditional intelligent network solution. The traditional program-controlled switches in LE and TE enable all nodes to have Service Switch Point ("SSP") capabilities, so that all services are triggered to the service control point 31 for service processing according to various conditions , and the service control point 31 becomes the service logic execution point of the network in FIG. 3 . In this evolution mode, on the one hand, the existing network resources can be fully utilized to realize a more flexible service provision platform; Centralized services are stripped from the switch, and only the basic control and switching functions are retained; and the service control point 31 can also evolve into a component of the service layer in the future network in the future evolution.

In this evolution mode, both TE and LE traditional program-controlled switches need to be upgraded to support SSP, complete basic control and switching functions, and do not have business logic capabilities. As for the uplink media interface, the traditional TDM interface can be retained, but it needs to support Interact with SCP through protocol to realize business.

Considering the current network situation, the above scheme has the following problems:

1) This evolution mode requires all switches to be upgraded, and the cost is high;

2) The cost of transformation is high: the models on the existing network are complex and numerous, and some of them must be upgraded, and some old and weak models are difficult to support even if they are upgraded;

3) High acquisition cost: It is necessary to realize the connection of online billing for many switch systems. Due to the number, model, and software version of switches, the investment cost and technical difficulty become a major barrier.

4) Difficulty in project implementation: For switches from many different manufacturers, different models, and versions to enter the entire network project, the cycle is long and the project implementation is difficult.

All in all, this solution also requires telecom operators to immediately upgrade the software and hardware of all program-controlled switches on the previous PSTN network. It also requires too high requirements for the transformation of the existing network of telecom operators, and the risk is relatively high.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a public switched telephone network evolution system and its method, so that existing equipment and network resources can be reused as much as possible, so that the cost is low, and the reuse rate of switches and their software is high , The difficulty of engineering work is relatively reduced.

To achieve the above object, the present invention provides a public switched telephone network evolution system, comprising a plurality of end offices, at least one service switching point, at least one service control point, and a billing center, wherein

The end office is used to forward all services to the service switching point;

The service switching point is used to receive the service from the end office, trigger the call of the service to the corresponding service control point according to predetermined conditions, and send the billing information to the billing center business information;

The service control point is used to process services from the service switching point;

The charging center is used for charging according to the service information from the service switching point.

Wherein, the service switching point also supports a packet interface and protocol, and the system further includes an application server connected to the service switching point through the packet interface and protocol, and is used to process the business from the service switching point .

The end office uses the call forwarding capability of the switch to forward all services to the service switching point through data configuration.

The function sets of the plurality of service control points include all service processing functions of the end office and the tandem office in the public switched telephone network.

The present invention also provides a method for the evolution of the public switched telephone network, comprising the following steps:

A end office forwards all services to the service switching point;

B. The service switching point receives the service, triggers the call of the service to the corresponding service control point according to predetermined conditions, and sends service information for charging to the charging center;

The service control point in C processes the services from the service switching point;

D. The charging center performs charging according to the service information from the service switching point.

Wherein, in the step A, the central office realizes the forwarding of all services through data configuration by using the call forwarding capability of the switching center.

The step B also includes the following sub-steps:

It is judged whether the service needs to be processed by the extended service platform, and if yes, the service is forwarded to the application server for processing.

Through comparison, it can be found that the difference between the technical solution of the present invention and the prior art is that firstly, the switch of the tandem office is transformed into a service switching point, so that it has a service switching function, and the call can be triggered to the corresponding switch according to different conditions. service control point in the tandem office for service processing; secondly, there is no need to upgrade the end office switch, it only needs to use its call forwarding function to forward all services to the service switching point in the tandem office through data configuration; thirdly, the billing center only needs to Obtain service information for charging from a service switching point.

The difference in this technical solution has brought obvious beneficial effects. First, since there is no need to transform a large number of end offices, it saves the upgrade cost of end office switches and reduces the overall evolution cost of PSTN;

Second, the billing center only collects business data for billing from the business exchange point, thus simplifying the data collection cost in the billing process;

Third, because only the tandem office needs to be transformed into a service switching point, the engineering amount is relatively small, and the evolution solution is relatively safe. There is no need to consider complex end office equipment, and large-scale replacement and upgrades are not required at one time.

Description of drawings

Fig. 1 is a schematic diagram of the basic networking structure of the PSTN network;

FIG. 2 is a schematic diagram of a separate evolution mode in the prior art;

FIG. 3 is a schematic diagram of an evolution mode of an intelligent network in the prior art;

Fig. 4 is the architecture diagram of the intelligent network based on the PSTN network;

Fig. 5 is a schematic diagram of an evolution mode of a gateway according to an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the principle of the present invention will be described in detail below to implement a less risky evolution solution by utilizing the basic service forwarding capability in the traditional program-controlled exchange and the transformation of the tandem office. And focus on the core content of the present invention: the evolution of the tandem office, the evolution of the billing center, and the evolution of the service control point.

Since the present invention refers to the evolution mode of the intelligent network in the TE part, the situation of the intelligent network based on the PSTN is described first.

As shown in Figure 4, according to the provisions of my country's intelligent network system, my country's intelligent network adopts a network system based on SSP. A business generation environment 40, a business management access device 41, a business management point 42, a business control point 43, and a business switching point 44 are configured in the network, and a national intelligent network is formed through the No. 7 signaling network. The main function of the service generation environment 40 is to generate intelligent network services, provide an environment for defining, developing and testing intelligent network services, and provide functions such as simulating network configuration and simulating the operation of service software in the network, which resides in the intelligent network system The highest level of structural logic. The service management access device 41 and the service management point 42 belong to the service management system. The two constitute a level, that is, the service management system level, which is responsible for managing the intelligent network and intelligent network services. It includes the management of services and the management of service users. Functions such as network management, network management, service management access and system access management are at the second layer in the logical hierarchy of the intelligent network architecture. The service control point 43 plays a role in controlling and processing intelligent services in the entire intelligent network system. It completes the service control function (Service Control Function, referred to as "SCF") and service data function (Service Date Function, referred to as "SDF"), and at the same time It accepts the management of the service management system, and is in the third layer of the intelligent network logic hierarchy. The service exchange point 44 mainly completes the service exchange function and call control function. When the service exchange point 44 is a local exchange, it also has the call control access function. The comprehensive service exchange point 44 also includes some special resource functions.

Fig. 5 shows a basic network diagram after the evolution mode is completed according to an embodiment of the present invention. As shown in the figure, the system consists of a separate billing center 50 and three layers, namely, a service layer 51 , a connection layer 52 , and an access layer 53 . Wherein, the service layer 51 is composed of a service control point 510 and an application server 511 , and the convergence layer 52 is composed of a service exchange point 520 and a service exchange point 521 . The access layer 53 is composed of a large number of end offices. In FIG. The main equipment in the end office is a traditional program-controlled switch.

Generally speaking, this solution only evolves the nodes in three parts, that is, it only needs to evolve the node devices included in the billing center 50, the service layer 51, and the convergence layer 52, while the original PSTN network has the largest number, The traditional program-controlled switches included in each end office of the access layer 53 with the largest investment, different manufacturers, different models, and different versions do not undergo major transformation, but only use the basic service forwarding capabilities of traditional switches to minimize the evolution risk.

The evolution of the different parts is generally described below.

First describe the evolution of the billing center 50:

In the evolution mode, the interface mode of the billing center 50 is very different from the original PSTN network, and also different from the two prior art solutions mentioned above. Comparing Fig. 5 with Fig. 1, Fig. 2, and Fig. 3, it can be clearly concluded that after the evolution of billing center 50, it does not need to interface with all end offices of access layer 53, but only needs to interface with all end offices of the original tandem office. It is only necessary to collect relevant charging information at the location, that is, the service switching point 520 and the service switching point 521 of the tandem layer 52 in FIG.

Next, the evolution of the service layer 51 is described: in the evolution mode, in the original PSTN network, the layer of the service layer 51 was not proposed separately, because the service of the original PSTN network was relatively simple and single, only the voice service, and the program control in the original PSTN network The switch only provides the basic call control of the No. 7 signaling system, and there is no need to propose a separate layer.

However, with the continuous evolution of the PSTN, an intelligent network system that uses a separate data network to provide advanced call control and enhanced service functions for the telephone network on the basis of the PSTN has emerged. It should be noted that the separate data network here refers to SS7 Network. The basic idea of the intelligent network is to separate the switching function from the control function, simplify the software of the switch, and make it only complete the basic connection function. The intelligent network architecture allows service providers to create business logic programs to improve PSTN call functions. The functional architecture of the intelligent network is defined in international standards as a series of functional module entities composed of multiple distributed functions. On the distributed function plane defined by the intelligent network protocol, the SCF is separated from the Service Switch Functions ("SSF" for short) and the Connect Control Function ("CCF" for short). The SSF and CCF functions provided by the service switching point 520 and the service switching point 521 support the basic call processing procedure of the voice service. The SCF function provides centralized service control logic for advanced services, which is provided by the service control point 510. When the SSF detects a basic call processing event, it negotiates with the SCF for operation instructions, that is, the service switching point 520 or the service switching point 521 and the service control point 510 signaling exchange. The SCF on the service control point 510 is responsible for instructing the SSF and CCF on the service switching point 520 or 521 to establish calls and support connections. In the business, management and control structure of the intelligent network, support functions are also defined. In addition, SDF allows service data to be separated from service control logic. In many practical applications, SCF and some SDF functions are often integrated into the service control point 510 . That is, a network element structure such as the service control point 510 appears in the original PSTN network.

With the rise of NGN, business logic processing and media processing are separated, that is, the idea of separation of switching and control becomes more prominent. The task of the service control point 510 level will increase, and the complexity is higher. It is necessary to replace the service control point 510 with a more powerful node device. Therefore, proposing a new service level can make the network level clearer and facilitate all levels. Functional division.

Therefore, in the evolution mode, it is also a protection point for the capability change of the service control point 510: the service control point 510 needs to undertake the smooth service evolution module during the evolution process, and gradually transition to the application server 511 that will replace them in the NGN network , of course, this module may also be directly evolved to the application server 511 to complete. In the evolution mode of this divisional proposal, the service layer 51 may be composed of a service control point 510 improved from the original SCP, or provide services directly through the application server 511 in the NGN or 3G network.

The evolution of the tandem layer 52 is then described:

The key to the evolution of the tandem layer 52 lies in the transformation of the traditional program-controlled switches in the TE.

At present, the traditional program-controlled switch in the PSTN network, that is, the circuit switch includes access functions, call control functions, switching functions, business functions, and signaling functions. These functions are all combined into a single switch, which is a vertically integrated, closed and single-vendor-specific system structure. Moreover, the circuit switch is based on circuit switching technology, which has some fatal weaknesses, such as low bandwidth utilization. On the basis of packet technology, NGN, which replaces the PSTN network, strives to separate service logic processing from media processing, that is, the separation of switching and control. On the control level, MGC is used to perform various control tasks. MGC breaks the The traditional closed switching structure adopts a completely different horizontal combination mode to open the interfaces between various functions of the switch, and adopts open interfaces and common protocols to form an open, distributed, and multi-vendor application system structure. At the same time, the IP network is used as the switching layer to realize "soft" switching. Comparing the functions of the circuit switch and the media gateway controller, it can be seen that many of the functions that the media gateway controller should have can be provided by the software of the current circuit switch, so that it is possible to use the functions of the circuit switch, especially the software. , to restructure to realize the functions that the MGC should provide. For example, through software control, the call control function in the circuit switch can be simplified to a basic call control function that has nothing to do with the business. Another example is the signaling function. Currently, the circuit switch has a signaling function, which can also be used by the MGC. Other functions such as billing, resource control, black and white lists, and call authentication can also be realized by modifying the software.

Each control and management unit in NGN can find the corresponding functional entity in the intelligent network: service control and support function provide value-added services, corresponding to the SCF of the intelligent network; service processing function, responsible for building components, corresponding to the intelligent network SCF and SDF; session management function, responsible for managing access, service provision, and communication connection, corresponding to SSF of intelligent network; connection management function, responsible for providing connection between packet network and Internet gateway, corresponding to CCF of intelligent network; The connection management function is responsible for managing the intercommunication with the existing PSTN service structure, including managing the triggering of the intelligent network and the control of the low-level gateway equipment, corresponding to the SSF and CCF of the intelligent network.

From the perspective of the corresponding relationship between the NGN and the intelligent network, those skilled in the art can understand that it is feasible to realize some functions of the MGC by transforming the circuit switch. It is also feasible to upgrade the traditional program-controlled switch in TE to have SSF and become an SSP, that is, to strip the centralized services of the traditional program-controlled switch in TE from the switch, and only retain the basic control and switching functions; Complicated processing is separated into the service control point 510 in the service layer 51 to complete. What needs to be explained is that this method is adopted in the evolution of the intelligent network, each traditional program-controlled switch is upgraded to an SSP, and a variety of new services are provided on the PSTN through the cooperation of the SSP and the SCP.

In this solution, it is necessary to protect this new evolution mode: the initial PSTN evolution is completed through the transformation of the original traditional program-controlled switch in the tandem office. The transformation mode is to upgrade its functional characteristics so that it has SSF. The switching nodes become the service switching point 520 and the service switching point 521, and can communicate with the intelligent network SCP through the protocol to realize services, that is, communicate with the service control point 510 in the service layer 51. Alternatively, services may also be provided directly through the application server 511 in the NGN or 3G network.

Finally, the evolution of the access layer 53 is described:

Compared with the two existing technical solutions mentioned above, in this solution, there is basically no change at this level, and compared with the evolution of the tandem office, the evolution of the billing center, and the evolution of the service control point, almost only a small amount of work has been done . It mainly utilizes the basic service forwarding capability of traditional program-controlled switches in the end office. End office 530, end office 531, end office 532, end office 533, end office 534, and end office 535 only need to do data and send all traffic to The service switching point 520 and the service switching point 521 in the convergence layer 52 .

The above describes the evolution of this solution in each part. As an overall solution, it is necessary to introduce the specific basic evolution mode of the entire evolution process in combination with Figure 5:

First, forward all the services of end office 530, end office 531, end office 532, end office 533, end office 534, and end office 535 to the upper-level TE through data configuration, that is, the service switching point 520 and service switching point in Figure 5 The tandem office where the 521 is located handles the processing, so that the software of the traditional program-controlled switches of these end offices remains basically unchanged, and only needs to use its call forwarding capability.

Next, the traditional program-controlled switch in the TE of the tandem layer is transformed into a service switching point 520 and a service switching point 521 with SSF, and the call can be triggered to the corresponding The SCP performs service processing, that is, the service control point 510 in FIG. 5 . It should be noted that the above process can also be described in detail: the service switching point 520 and the service switching point 521 need to add some checkout points and control points in the call processing process, and the checkout points can report various events that occur during the call process to The service control point 510 reports and waits for further control commands from the service control point 510 . The service switching point 520 and the service switching point 521 accept the control command of the service control point 510 to realize the control of the calling process.

Subsequently, the service control point 510 in the service layer 51 needs to implement the traditional services completed by all end offices and tandem offices to achieve smooth service evolution; of course, if the tandem office directly supports some packet interfaces and protocols, it can also directly Provide services through the AS in the NGN or 3G network, that is, the application server 511 in the service layer 51 provides services;

Thereafter, since all services are forwarded to the original end office position, the billing center 50 only needs to interface with the new SSP node, that is, the interface of the billing center 50 only needs to communicate with the service switching point in the tandem layer 52 520. The service exchange point 521 can extract the required data for charging processing if it wants to connect.

Finally, SCP can be smoothly integrated into the business platform in the future and can be smoothly transitioned. That is, the service control point 510 in the service layer 51 in Figure 5 no longer becomes a logical entity on the traditional program-controlled switch during evolution, but is integrated into the service layer, because at this time, the traditional switch has evolved to MG, MGC and Each functional unit such as the signaling gateway, so the SCP control function can be further replaced by the MGC, the service layer 51 will be entirely composed of AS, and the intelligent network service can also be integrated into the NGN network.

It can be seen from the above description that in this solution, the evolution of the traditional PSTN network is realized by making full use of the basic service forwarding capability of the traditional switch and the transformation of the tandem office. Various new and old services enjoyed by end users will be supported by the intelligent network of the evolved SSP at the service layer and SCP at the service layer, or a hybrid network formed by SSP at the connection layer and AS at the service layer to form a hybrid network of intelligent network and NGN.

Those skilled in the art can know that, with a basic telecommunication service—no answer forwarding service, this service is a solution to transfer to other numbers when the called user is busy, and it provides the user with a , a service that is still able to handle incoming calls. This new service can be provided by the pure NGN network composed of MG and MGC, and can also be provided by the evolved network of the present invention. The specific implementation in this evolution plan is as follows:

First, it is triggered by the SSP of the service switching point 520 or the service switching point 521 in the network of FIG. 5 . When the called user registers this service and no one answers the call timeout, this service is activated. At this time, because the upgraded traditional program-controlled exchange of the TE tandem office has the SSF function, it can directly trigger the forwarding when no answer is received. business;

Next, the detection point of the service switching point 520 or the service switching point 521 may report the event occurring during the call to the service control point 510 and wait for further control commands from the service control point 510 .

Then, because the corresponding business logic has been added on the service control point 510, that is, for the no-answer call forwarding service, the SCP only needs the pre-registered number of the user to whom the call is connected, so the service control point 510 is responsible for this event. In response, a control command is sent to the service switching point 520 or the service switching point 521 .

Finally, the service switching point 520 and the service switching point 521 accept the control command of the service control point 510, initiate a call to the pre-registered number according to the control command, and complete the service.

For end users, there is no difference between these new and old services and the services provided by the pure NGN network composed of MG and MGC. Therefore, this evolution solution can be competent for various network services for a long period of time, achieving smooth Evolution, reuse existing equipment and network resources as much as possible, protect telecom operators' investment, and avoid evolution risks to the greatest extent.

Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein, and without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (7)

1. a public switched telephone network evolution system is characterized in that, comprises charging center, a plurality of end office (EO), at least one Service Switching Point and at least one service control point, wherein

Described end office (EO) is used for all business are forwarded to described Service Switching Point;

Described Service Switching Point is used to receive the business from described end office (EO), and according to predetermined condition, the calling of described business is triggered to corresponding described service control point, and sends the business information that is used to charge to described charging center;

Described service control point is used to handle the business from described Service Switching Point;

Described charging center is used for according to chargeing from the business information of described Service Switching Point.

2. public switched telephone network evolution system according to claim 1, it is characterized in that, described Service Switching Point is also supported packet interface and agreement, and, described system also comprises an application server, this application server is connected with described Service Switching Point with agreement by described packet interface, and it is used to handle the business from described Service Switching Point.

3. public switched telephone network evolution system according to claim 1 is characterized in that, described end office (EO) utilizes the call forward ability of switch, by data configuration all business is forwarded to described Service Switching Point.

4. public switched telephone network evolution system according to claim 1 is characterized in that, the function intersection of described a plurality of service control points comprises all service processing function of end office (EO) and tandem exchange in the public switched telephone network.

5. a public switched telephone network evolution method is characterized in that, comprises following steps:

A end office (EO) is forwarded to Service Switching Point with all business;

The described Service Switching Point of B receives described business, and according to predetermined condition, the calling of described business is triggered to the corresponding service control point, and sends the business information that is used to charge to the charging center;

The described service control point of C is handled the business from described Service Switching Point;

The described charging center of D is according to chargeing from the business information of described Service Switching Point.

6. public switched telephone network evolution method according to claim 5 is characterized in that, in the described steps A, described local side utilizes the call forward ability of exchange, by data configuration, realizes the forwarding of all business.

7. public switched telephone network evolution method according to claim 5 is characterized in that, described step B also comprises following substep:

Judge whether described business is the platform processes business of need activating business, if then described business is forwarded to application server and handles.

Images