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China Telecom farewell program-controlled exchange: the world's first all-optical network / all-IP network operators

via:快科技     time:2017/12/21 21:32:06     readed:531

Li Xiangning, Deputy Director of Communication Administration of Ministry of Industry and Information Technology, Wei Leping, Deputy Director of Science and Technology Committee of Ministry of Industry and Information Technology, Chen Jiezhong, Director of Shanghai Communication Administration, Sun Xiaohong, General Manager of Network Operation and Maintenance Department of China Telecom and Ma Yiming, General Manager of China Telecom Shanghai Co., attend.

Sun Xiaohong said:"The TDM PBX is a microcosm of the rapid growth of the communications industry and the power outage of our last switching office is a milestone."

In 2014, China Telecom launched a large-scale customer premise withdrawal network. After 4 years, 47575 end-office PBX switches were withdrawn and 110 million users were relocated.This is also the world's largest user of TDM switching network migration, called the telecommunications industry a pioneering act.

After calculation, TDM program-controlled switching equipment 4 years net withdrawal of 16.82 billion kWh, equivalent to 1.677 billion kg of carbon dioxide emissions.

In 2016, China Telecom released the white paper on CTNET2025 network architecture and started in an all-round wayNetwork intelligent reconstruction, Introducing the world's leadingSDN / NFV technology, And build a new network of simplicity, agility, openness and intensiveness through the framework of basic cloud resource layer, software-based network function layer and collaborative layout layer.

China Telecom network reconfiguration is expected to be fully completed by 2025. Next-generation network will be able to achieve the following objectives: First, significantly enhance the network capacity and performance, create a strong new generation of information infrastructure; Second, business and technology innovation to promote cost reduction Thirdly, it will create a new and open eco-environment and support the new engine of "double creation" to provide rich network services to users. Fourth, to lead and support the Chinese enterprises to "go global" through technical innovation, .

December 14 this year, China Telecom "Middle and Lower Reaches of the Yangtze River ROADM network" officially put into use, this is China's first large-scale commercial ROADM network, network size, technology level among the highest in the world.

The ROADM network enables the rapid delivery, automatic scheduling and recovery of the transport network at the optical layer and the resilience to multiple "broken fibers". As a result, the optical network evolves from a traditional non-networked point-to-point link to an optical network. Transmission of major technological changes in the field.

At present, China Telecom has built the largest fiber broadband network in the world with 312 million fiber-to-the-home (FTTH) optical ports and 150 million broadband users, ranking the first in terms of overall network size and number of subscribers.

Extended reading -

TDM switch:

Instantaneous division multiplexing mode, which is what we generally say program-controlled telephone switches, using time division multiplexing (TDM) technology and large scale integrated circuits.

Time Division Multiplexing is a digital multiplexing technique that refers to a technique of transmitting multiple digitized data, voice and video signals over the same communications medium, through cross-bit pulses in different channels or time slots.

Telephone networks are based on TDM technology, so their networks or devices are often referred to as TDM networks or devices.

The services provided by TDM equipment include supplementary services such as basic voice service such as call service, call transfer, and caller ID display. Together with the intelligent network, intelligent services such as 400 and 800 are provided.

At the initial stage of reform and opening up, the national public telephone network had a capacity of only 4.35 million with only 2.14 million telephone subscribers. The telephone penetration rate was only 0.38%, less than one tenth of the world average. China Telecom broke international conventions and dared to introduce and popularize the program-controlled switches using TDM technology that was just commercially available in the world at that time.

On December 24, 1980, the Fujian Provincial Posts and Telecommunications Administration and Japan's Fujitsu Co., Ltd. formally signed the contract of introducing "F150 Program-controlled Telephone Switchboard" to introduce 10,000 gateways to the local telephone exchange system for Fuzhou Telecom Bureau and long-distance exchange of 600 lines. November 27, 1982, China's first program-controlled telephone exchange F150 enabled in Fuzhou. China Communications began to embark on a high starting point, a great leap forward journey.

The communications construction has continuously met the needs of the national economy and social development. The scale, capacity and level of technology of the communications network have entered the advanced ranks in the world. The telecommunications industry has been transformed from a "bottleneck" of national economic development during the initial stage of reform and opening up to a " engine".

More than 30 years ago, TDM PBX was the most advanced communication equipment in the world at that time. However, with the rapid development of technology in the communications industry, IP-based IMS and softswitch equipment have been mature and deployed on the Internet with the replacement of TDM switching equipment Capacity, while a large number of TDM switches in the network running time of more than 20 years, equipment aging failure rate and can not provide users with video calls and other multimedia new business, and TDM switch energy consumption, nor in line with the concept of green development.

IMS network:

IMS (IP Multimedia Subsystem), IP Multimedia Subsystem, is a new form of multimedia services to meet the current end-customers more innovative, more diversified multimedia business needs.

IMS has become the core network standard architecture for the all-IP era by supporting multiple access and rich multimedia services.

After experiencing the maturity of the past few years, nowadays, IMS has crossed the rift and become the mainstream choice of VoBB and PSTN network transformation in the field of fixed voice. It has also been confirmed by 3GPP and GSMA as the standard framework of mobile voice.


VoLTE (oice over LTE) is an IMS-based voice service. It is an IP data transmission technology. All services are carried on a 4G network, enabling data and voice services to be unified on the same network.

In other words, 4G networks not only provide high-speed data services, but also provide high-quality audio and video calls. The above goals are achieved through the VoLTE technology.


(Reconfigurable Optical Add-Drop Multiplexe) A reconfigurable optical add-drop multiplexer, a device or device used in a dense wavelength division multiplexing (DWDM) system, which can be remotely reconfigured to dynamically Business wavelength on or off the road.

In the middle of the line, you can arbitrarily assign the wavelengths of the upstream and downstream services according to your needs to implement flexible scheduling of services.

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