er carrier, and origi- nated in the United States. Total Access Communication System (TACS)-TACS operates in the 900MHz band, offers 1,000 channels, and originated in the United Kingdom. Japanese Total Access Communication Systems (JTACS)-JTACS works in the 800MHz to 900MHz band, and it comes from Japan. Chapter 14 Wireless WANs Nordic Mobile Telephone (NMT)-The original variation of NMT was 450MHz, offering some 220 channels. NMT had a very large coverage area, thanks to its operation at 450MHz (you could probably travel through half of Scandinavia and still be within one cell), but the power levels are so intense that mobile sets were incredibly heavy. NMT originated in Den- mark, Finland, Norway, and Sweden. Other 1G standards used in Europe include Germany and Austria's C-Netz, Swe- den's Comvik, NMT-F (France's version of NMT900), and France's Radiocom 2000 (RC2000). The cellular radio system has three key components (see Figure 14.1): a trans- ceiver station, a mobile telephone switching office (MTSO), and a mobile unit (i.e., the phone). Each cell needs a base transceiver station-a tower that transmits sig- nals to and from the mobile unit. Each of these base transceiver stations connects to an MTSO. The MTSO then interfaces into the terrestrial local exchanges to com- plete calls over the PSTN. The connections from the base transceiver stations to the MTSO can be either microwave or wireline, and then typically from the MTSO to the local exchange there is a wireline facility, but it could also potentially be micro- wave. (Chapter 2, "Traditional Transmission Media," discusses the various media options in detail.) When a mobile unit is on, it emits two numbers consistently: the electronic identification number and the actual phone number of the handset. These are Telephone Land Line Local Exchange Microwave or Wireline = Base Transceiver Station (BTS) MTSO = Mobile Telephone Switching Office = Mobile Unit (mobile station) = Microwave or Wireline Figure 14.1 The analog cellular architecture 1G: Analog Trans