 DL: 1.805GHz to for most existing car- services in Europe. 1.880GHz riers and a few new GSM is considered a entrants. DCS air interface. Appendix Technology Frequencies Features Comments Enhanced Special- UL: 806MHz to Nextel (now part of Nextel and other SMR ized Mobile Radio 821MHZ Sprint Nextel) ser- operators use iDEN (ESMR) DL: 851 MHz to vices operate on these technology developed 866MHz frequencies. by Motorola to support voice, paging, push- to-talk, and messaging on the same telephone. Also suitable for 4G service. *2.5-generation services (2.5G) Many GSM mobile operators deployed these packet data services in the interim to 3G. They use the same spectrum as GSM. This is a lower- cost solution than 3G but with less efficient spectrum utilization. Same as GSM, General Packet Radio Appropriates voice DCS, and PCS Service channels for data; 40- to 60Kbps. Enhanced Data Rates Data speeds of about for GSM Evolution 110Kbps. Requires fewer voice channels for data than GPRS. *Third-generation services (3G) 3G packs more services into a given amount of spectrum than 2.5G technology. Mobile and Wi-Fi Networks Table 7-3 (Continued) Technology Frequencies Features Comments WCDMA, also IMT-2000 bands: More capacity for Carriers launched called UMTS UMTS: voice, higher-speed value-added 3G CDMA2000 1X data, acceptable video, services to generate Uplink: 1.885GHz low-latency appli- higher revenues. CDMA2000 to 2.025GHz (in cations, and SO on. the United States: CDMA2000 1xEV- 1xEV-DO Standards bodies have UMTS TDD 1.71GHz to DO (data optimized) is specified all of these 1.755GHz) always combined with TD-SCDMA frequency bands for 3G CDMA2000 1X (voice Downlink: services. and data) on a single 2.11GHz to chip. 2.17GHz (in the United States: WCDMA is normally 2.11GHz to combined with GSM 2.155GHz) on a single chip for voice services. CDMA2000: UMTS TDD uses one 450MHz (NMT), frequency band for 800MHz, 1.7GHz uplink and downlink (Korea), 1.9GHz data transmissions. (PCS), and 2.1GHz (UMTS) The Chinese govern- ment commerc