Shanghai, referred to as "Shanghai" or "Shen" for short, is the birthplace of the Communist Party of China (CPC), a municipality directly under the Central Government of the People's Republic of China, a national central city, a megacity, a core city of Shanghai, Hangzhou and Ningbo, an international economic, financial, trade, shipping and scientific and technological innovation center, and the first batch of coastal open cities.
The switch structure in People's Republic of China (PRC) adopts a four-level tandem radiation long-distance telephone network: C 1 is a regional central office or switch, which is located in eight major cities: Beijing, Shanghai, Shenyang, Nanjing, Wuhan, Chengdu, Xi and Guangzhou. C2 Bureau is a provincial central bureau, which is located in the provincial capital cities other than C 1 Bureau. Bureau C3 is a regional central bureau. C4 Bureau is a county-level exchange center.
Reference: Baidu Encyclopedia-Telephone Area Code