On this day, 32 years ago, on October 15, 1993 (September 1, 1993 in the lunar calendar), the world's longest optical cable ran through China. On October 15, 1993, the optical fiber communication trunk line running through Beijing, Hebei, Henan, Hubei, and Hunan to Guangzhou, and extending south and west to Haikou and Nanning, passing through eight provinces and cities and 22 prefectures and cities, with a total length of 4700 kilometers. Officially opened in Beijing today. This is currently the longest optical cable trunk line in my country and the longest in the world. The project has a total investment of more than 500 million yuan and can provide more than 105,000 long-distance circuits. The Beijing-Han-Guangzhou route is located at the "backbone" of my country's communications. In the past, inter-regional communications mainly communicated through the mid-coaxial cable analog carrier system built in the 1980s and the transformed microwave communication system. As my country's reform and opening up continues to deepen, the contradiction between supply and demand for communications along the route has become increasingly prominent, and the long-distance telephone connection rate is less than 10%. In order to alleviate this contradiction, the Ministry of Posts and Telecommunications and local governments invested a total of 312 million yuan to build this 3074-kilometer-long Beijing-Han-Guangzhou optical cable trunk line. It is my country's first domestically developed, produced and constructed optical cable primary trunk line that is fully domestically produced. For the first time, the project adopts a new generation of fourth-order group transmission system developed by the Wuhan Research Institute of the Ministry of Posts and Telecommunications that is suitable for my country's national conditions. The capacity is expanded by 62.5% compared with similar foreign systems; it can provide 98,000 long-distance circuits. The Guangzhou-Yong optical cable trunk line is 804 kilometers long and the Guangzhou-Qiong optical cable trunk line is 858 kilometers long, providing 12240 and 18840 circuits respectively. The completion and commissioning of this communication trunk line can greatly relieve the communication tension, and the social benefits are very significant.