Why are the 3g standards of the three major operators different?

China Unicom, China Mobile and China Telecom adopt different 3G technical standards. In May, 2, the International Telecommunication Union (ITU) determined three mainstream wireless interface standards: W-CDMA, CDMA2 and TDS-CDMA. Among them, China Unicom uses WCDMA standard, China Telecom uses CDMA2 standard, and China Mobile uses TDS-CDMA standard. W-CDMA: WidebandCDMA, which means wideband code division multiple access. Its supporters are mainly European manufacturers with GSM system, and Japanese companies also participate in it to some extent, including Ericsson, Alcatel, Nokia, Lucent and Nortel in Europe and America, as well as NTT, Fujitsu and Sharp in Japan. CDMA 2: CDMA 2, also known as CDMA Multi-Carrier, was proposed by Qualcomm North America Company of the United States, with Motorola, Lucent and Samsung of South Korea all participating, and South Korea is now the leader of this standard. TD-SCDMA: This standard is a 3G standard independently formulated by Chinese mainland. On June 29th, 1999, China Institute of Telecommunications Science and Technology (Datang Telecom) proposed it to ITU. (The above content is only applicable to Guangdong Unicom users)