The mobile phone market is divided between AT&T Mobility (formerly AT&T Wireless - www.att.com ), Verizon Wireless (formerly Bell Atlantic Mobile - www.verizon.com ), Sprint Corporation (sprint.com ), and T-Mobile (www.tmobile.com ).
The primary digital cell phone technologies are TDMA, CDMA, iDEN, and GSM. The GSM standard was designed to work across the whole of Europe, and all European nations and some Asian nations chose it as their sole standard for this reason, while in Japan and South Korea another single standard, CDMA, was selected. In the United States there was no such standardization. Since America is a huge territory, cell phone coverage is a big source of complaint, although efforts are being made to improve this.