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The original cellular technology was based on an analog signal. During the 1990s the new PCS digital mobile phone technology was introduced. PCS stood for Personal Communication System, and Sprint being one of the first companies to adopt this started their digital phone division, called Sprint PCS. == AMPS ==This technology is mentioned for historical purposes. Although radio phones or a proto cell phone technology can be traced back to the 1950s, Advanced Mobile Phone System (AMPS) is considered the first true cell phone network commercially available to the United States, starting in 1978. AMPS communication was unencrypted, so people to listen in on cell phone conversations with an ordinary police scanner. Phones were often cloned, causing issues of fraud and network abuse. AMPS was also a bandwidth hog, using a Frequency-division multiple access (FDMA) scheme that required significant amounts of wireless spectrum.AMPS started to get phased out beginning in the 1990s when PCS digital was introduced. Verizon Wireless operated an AMPS network, and on February 18, 2008, Verizon discontinued all AMPS service. The last of the AT&T AMPS network was shut down February 18, 2008. == TDMA ==This is an outdated technology. The major TDMA carriers switched over to GSM. AT&T (including the former AT&T Wireless) and US Cellular were formerly on the TDMA standard. US Cellular actually went to CDMA. A Mobile Virtual Network Operator (MVNO) is a cell phone company that doesn't own any wireless spectrum, but instead buys it from a network operator such as Sprint. Essentially, an MVNO is a marketing company that believes it can build a profitable business targeting niche markets such as Hispanics or teenagers. Prior to 2006, most MVNOs offered prepaid service, with TracFone and Virgin Mobile among the notable-name providers. == Data ===== 1xEVDO ===