The communications companies in the United States are:
1 Verizon Communications, Verizon Communications USA
2 SBC Communications, Southwestern Bell Telecommunications USA
3 Qwest Communications Qwest Communications USA
4 AT&T Telephone and Telegraph USA
5 MCI Microwave Communications USA
6 Sprint USA
7 BellSouth BellSouth America
8 Comcast Comcast America
Domestic telecom operators use technology from the United States. The technologies of the three domestic operators:
1 China Unicom’s WCDMA network is the most mature, with more than 130 WCDMA networks in commercial use around the world. European standards, patents are relatively scattered, Qualcomm, Ericsson, etc. all hold patents, the theoretical downlink rate is 7.2M/s, currently 70% of the world's operators are operating, mainly China Unicom, AT&T, Vodafone.
2 Telecom’s CDMA 2000 network is the lowest cost and smoothest upgrade solution. The American standard, an upgraded version of CDMA 1X, is led by Qualcomm in the United States. The theoretical downlink rate is 3.1M/s or 9.3M/s. It is currently operated by 30% of global operators, mainly China Telecom, Verizon, and KDDI.
3 The mobile TD-SCDMA network is the third generation mobile communication network independently developed by China. Currently only China Mobile is operating. The theoretical downlink rate is 2.8M/s.