Detailed introduction to the general structure of Softswitch Technology

Many people may not have a special understanding of the Softswitch technology. So I have studied the general structure of the Softswitch technology in detail. I will share it with you here, hoping it will be useful to you.

1. General Structure of the softswitch network

The Softswitch technology adopts the advanced architecture of telephone switches and uses IP packets in the IP network to carry various information such as voice, data, and multimedia streams. A Programmable telephone switch can be divided into three functional modules: business access, route selection (switch), and business control. Each function module is connected to a whole through the switch's internal switching network. The Softswitch technology is to separate the above three functional modules, which are implemented by different physical entities. At the same time, some functional extensions are carried out, and various physical entities are connected through a Unified IP network, constitute a Softswitch Network.

The business access function module of the telephone switch corresponds to the edge access layer of the softswitch network; the routing selection (switching) function module corresponds to the control layer of the softswitch network; the business control module corresponds to the business application layer of the softswitch network, and the IP network forms the core transmission layer of the softswitch network.

2. Edge access layer

The Softswitch technology makes the service access module of the telephone switch an independent physical entity called the media gateway (MG). The MG function is to connect various users and services to the softswitch network by various means, MG completes data format and protocol conversion, and converts all media information flows connected to IP-based data packets for transmission in the softswitch network.

MG can be subdivided into the following categories based on different users and businesses connected to MG. Relay Media Gateway (TG): Used to complete relay connection with the PSTN/PLMN telephone switch and convert the 64 kbit/s voice signal in the PCM relay of the telephone switch to an IP packet. Signaling Gateway (SG): used for completing the Signaling connection with the PSTN/PLMN telephone switch, and converting the signaling information of the telephone switch based on the TDM circuit to the IP package.

TG and SG jointly complete the connection between the softswitch network and the PSTN/PLMN telephone network switched using the TDMA circuit, and connect the common telephone users and their services in the PSTN/PLMN network to the softswitch network. Access Gateway (AG): provides analog user line interfaces for directly connecting normal telephone users to the softswitch network. It can provide all services provided by the PSTN, such as telephone services and dial-up Internet services, it directly encapsulates user data and user line signaling in the IP package.

Integrated Access Device (IAD): A class of IAD provides both analog user line and Ethernet interfaces for accessing general telephones and computer devices, it is applicable to users who use telephone services and computers to use data services separately. The other type of IAD Only provides Ethernet interfaces for accessing computer devices, it is applicable to users who use telephone services and data services on computers at the same time. In this case, a dedicated "softphone software" needs to be installed on users' computer devices ". Media Servers Access Gateway (MNS) is used to complete information about various multimedia data sources and adapt Multimedia Streams mixed with video and audio to IP packets. H.323 Gateway: used to connect an IP address Telephone Network Gateway using the H.323 protocol. Wireless Access Gateway (WAG): used to connect Wireless Access users to the softswitch network.

It can be seen that AG, TG, and SG have jointly completed the functions of the telephone switch service access function module, and achieved the access of voice services of ordinary PSTN/PLMN telephone users, and adapt the voice information to an IP packet suitable for transmitting in the softswitch network. At the same time, the Softswitch technology also expands the service access function, which is embodied in several types of media gateways, such as IAD, malong, H.323 GW, and WAG. Through various MG and Softswitch networks, PSTN/PLMN users, H.323 IP telephone network users, common wired telephone users, and wireless access users' voice, data, and multimedia services are integrated.

3. Control Layer

The Softswitch technology independently converts the switch module of a telephone switch into a physical entity called a soft switch (SS ), the main function of SS is to control the business of all media gateways in the edge access layer and the communication between media gateways. The specific functions are as follows.

(1) determine the user's business use permissions based on the user attributes registered on the relevant servers of the business application layer to determine whether to accept the business requests initiated by the user.

(2) control the resources of various media gateways at the edge access layer, control the use of resources of each media gateway, and master the resource usage of each media gateway, to determine whether there are sufficient network communication resources to meet the business requirements applied by the user.

(3) Complete the routing selection function of the call, and determine which media gateways should establish communication connections based on the information related to the user's business request, the media gateway is notified to establish communication connections and communicate with each other, as well as the information compression and encoding methods used during the communication process, and whether ECHO suppression is enabled.

(4) monitors and controls the communication connection status between media gateways, and instructs the corresponding media gateways to disconnect after the user completes business use.

(5) billing. Because the soft switch only controls the connection of services, and the data streams between users do not pass through the soft switch, the soft switch can only be charged by the connection duration, but cannot be charged by the amount of information. If a soft switch is required to be charged by the amount of information, the media gateway is required to collect statistics on the amount of information used by each user each time, and send the statistical results to the soft switch.

(6) access to (GK) Interactive Routing and other messages with the H.323 network to achieve intercommunication between the softswitch network and the H.323 IP address telephone network.