The new Softswitch technology standard is released to guide the Next Generation Network

The new Softswitch technology standard is released as next-generation network guidance. NGN is the core technology of softswitch, involving issues such as SIPSessionInitiationProtocol, H.248/MEGACO Protocol, and SIGTRAN protocol signaling transfer protocol.

The Softswitch technical standard is the control function entity of the Next Generation Network. It provides Call Control and Connection Control functions for businesses with real-time requirements for the Next Generation Network NGN and is the core of call and control for the Next Generation Network. Softswitch is located at the control layer of the Next Generation Network (NGN) and evolved from the call server CallServer proposed by some vendors) or the media gateway controller.

China's Ministry of Information Industry, China Telecom transmission Institute, defines the technical standard of softswitch as: "Softswitch is one of the core devices for network evolution and next-generation grouping networks. It is independent of the transmission network, it provides call control, resource allocation, protocol processing, routing, authentication, billing, and other functions. It also provides users with all the services available to existing circuit switches, it also provides third-party programmable capabilities."

As the core of NGN, The Softswitch technology standard is the coordination center between the Circuit Switching Network and the IP network. By controlling various media gateways, the service layer fusion between different networks is realized. The protocols used by Softswitch are controlled through negotiation in the communication system, and the Protocols must be available accordingly. In the NGN architecture, as the control center, Softswitch is implemented by supporting multiple protocols such as H.248/MEGACO, SIP, SIGTRAN, BICC, and H.323.

SIPSessionInitiationProtocol) Protocol: according to the definition of IETFRFC2543, SIP is an application layer control protocol used to create, modify, and end multimedia sessions or calls. These multimedia sessions include Internet Multimedia conferences, distance education, Internet telephones, and other applications.

The SIP protocol can be transmitted over TCP or UDP. Because the SIP itself has a handshake mechanism, UDP is preferred. According to the survey, the number of vendors that support the SIP protocol has increased significantly. The SIP protocol is widely accepted as the core protocol for multimedia services and applications, including 3G mobile multimedia.

H.248/MEGACO Protocol: this protocol is a gateway control protocol jointly promoted by ITU and IETF. After resolving the complexity and poor scalability of H.323, H.248/MEGACO is widely supported by manufacturers and becomes a key media gateway control protocol for the Next Generation Network.

SIGTRAN protocol signaling Transfer Protocol): SIGTRAN is the protocol that transfers circuit exchange signaling in the IP network, mainly the No. 7 signaling), through the signaling gateway SG. In our country's specifications, the signaling gateway is used to connect the No. 7 network and the IP network, and relay, translate or terminate signaling information.

As the core technical standard of softswitch for next-generation network control, it combines the advantages of traditional telephone network reliability and the flexibility and effectiveness of IP technology, and is an important concept of the transition from a traditional circuit switching network to a segmented network. It is worth noting that the development of NGN lies not only in softswitch, but also in the overall technological progress at each layer. For example, DWDM, optical network technology, API interface technology on the business layer, and various wide and narrow band access technologies such as LMDS and XDSL on the access layer ).

Problems Existing in the softswitch technical standards although many manufacturers have released the softswitch solution, and operators are actively conducting related tests, the application of the new technology needs to be improved for a long time, from the solutions provided by the current manufacturers, the main problems are:

International experience in networking and operation of large networks

After long-term operation and accumulation, traditional telecommunication networks have mature experience in network organization. However, Softswitch-based network organizations do not yet have mature experience at home and abroad, the use of fully-plane structure based on Softswitch or regional routing structure remains to be further explored in terms of technology and practice.

The Protocol has not been compatible, and the standards are still under development.

The selection of softswitch technical standards from different manufacturers and the compatibility of the protocols are difficult to achieve mutual compatibility. BICC protocol, SIP-T protocol and H.248 protocol are also under development, protocol options require operators to further determine according to business needs.

APIS do not have mature products

Based on an open business platform and standard API interfaces, this platform has created a bright future for network operators to provide new services. However, relevant products are still being explored and developed.
◆ QoS has no final solution
◆ Currently, the main solution only provides voice services, and new services are actively being developed and tested.
◆ Further development is required for multimedia services
◆ Network security problems
◆ Third-party business model issues
◆ Manageable business issues

The existence of the above problems will not hinder the application of new Softswitch technology standards and technologies. On the contrary, the operator will work with the equipment supplier to calmly solve these problems and actively conduct tests and continuously improve them.