Measure the test taker's understanding about the functions of Softswitch technology.

Softswitch technology plays a very important role in the next generation network. This is a consensus and has aroused great repercussions in the industry. With the increasing development of the telecom market and the Development of the Next Generation Network (NGN) as the key role of Softswitch technology, it is increasingly becoming the technical link for circuit switching and group switching networks to integrate. Therefore, the application of Softswitch technology in telecommunication networks has attracted more and more attention from the telecommunication industry.

The International Softswitch Association (ISC) defines Softswitch as "Softswitch is a software entity that provides call control functions ". China's Ministry of Information Industry, China Telecom transmission Institute, defines the Softswitch technology as "Softswitch is one of the core devices for network evolution and next-generation grouping networks. It is independent of the transmission network and mainly implements call control, resource allocation, protocol processing, routing, authentication, billing, and other main functions. It can also provide users with all the services available for existing circuit switches, it also provides third-party programmable capabilities." Softswitch has ten functions:

I. Media Gateway Access Function

The media gateway function is a set of endpoints/Network Relay or multiple endpoints connected to an IP network. It is an interface device between a group network and an external network, provides media stream ing or code conversion functions. For example, PSTN/ISDNIP relay media gateway, ATM media gateway, user media gateway, and Integrated Access Gateway, supports MGCP and H.1248/MEGACO protocols for resource control, Media Processing Control, signal and event processing, connection management, maintenance management, transmission, and security.

Ii. Call Control and handling functions

The call control and processing functions are one of the important functions of softswitch, which can be said to be the soul of the entire network. It can provide control functions for the establishment, persistence, and release of basic business/multimedia business calls, including call processing, Connection Control, Intelligent Call trigger detection, and resource control. Supports two-party call control and multiple-party call control functions. The multiple-party call control functions include the special logical relationship between multiple-party calls and the addition, exit, isolation, and listening of call Members.

3. functions provided by the business

During the evolution from circuit switching to group switching, the Softswitch technology must be able to implement all services provided by the PSTN/ISDN switch, including basic and supplementary services, it should also work with existing intelligent networks to provide intelligent services, or cooperate with third parties to provide a variety of value-added and intelligent services.

Iv. interconnection functions

The next generation network is not an isolated network, especially in the development and evolution of the existing network to the next generation network, it is inevitable to achieve collaborative work, interconnection and smooth evolution with the existing network. For example, the signaling gateway can be used to achieve intercommunication between the sub-network and the existing Signaling Network No. 7; the signaling gateway can be used to communicate with the existing intelligent network to provide users with a variety of intelligent services; you can use the H.323 protocol to connect to the IP telephone network of the existing H.323 system. You can use the SIP protocol to connect to the future SIP network system. You can use the SIP or BICC protocol to connect to other Softswitch technologies; it also provides interconnection between H.248 terminals, SIP terminals, and MGCP terminals in the IP network.

V. protocol functions

Softswitch is an open, multi-protocol entity. Therefore, various standard protocols must be used to communicate with various media gateways, application servers, terminals, and networks, protects user investment to the maximum extent and gives full play to the role of existing communication networks. These protocols include H.323, SIP, H.248, MGCP, SIGTRAN, RTP, and INAP.

Vi. resource management functions

Softswitch should provide resource management functions to centrally manage various resources in the system, such as resource allocation, release, configuration and control, resource status detection, and resource usage statistics, set resource usage thresholds.

VII. Billing Functions

Softswitch should have the function of collecting detailed phone numbers and duplex count, and be able to send the phone numbers to the corresponding billing center as needed by the operator.

VIII. authentication and authorization functions

Softswitch should support the local authentication function, which can authenticate and authorize users and media gateways in the jurisdiction to prevent access of illegal users/devices. At the same time, it should be able to connect with the certification center and send the user and media gateway information in the jurisdiction to the Certification Center for access authentication and authorization to prevent access by illegal users and devices.

IX. Address Resolution

The Softswitch device should be able to convert the E.164 address to the IP address, the alias address to the IP address, and the redirection function. For the number analysis and storage functions, the Softswitch technology is required to support the storage of the caller number 20 bits, the called Number 24 bits, and the ability to analyze the 10 bits and then select routes, the ability to add or delete numbers anywhere.

10. voice processing functions

The Softswitch device should be able to control whether the media gateway adopts voice signal compression and provide selectable voice compression algorithms. The algorithms should include at least G.729 and G.723.1, and G.726. At the same time, it can control whether the media gateway uses the echo cancellation technology and set the size of the dialog package cache area to reduce the impact of jittering.