Analog or AMPS is the origianl cellular service, It is available throughout North America as well as in many other countries. AMPS service is available in virutally every community in North America as well as along the highways that interconnect our towns and cities. A major problem with AMPS service is that it does not use the avialble radio spectrum very efficiently. One call requires one channel. Therefore a cell site can only handle as many conversations as it has channels. Whenever the system is at capacity, it may be difficult to make or receive calls. If you are moving, and not necessarily in a car, you may be switched, or handed off, to a different cell site. If this new cell site has no available channels, you are instantly cut off.Digital systems can carry multiple calls on a single channel. This will vary depending on the digital system. TDMA and GSM can have 5 to 7 calls on a single channel. CDMA can carry over 15 calls on a single channel. This is much more efficient for the service provider, but it also makes it more likely that you will be able to make and receive calls on a digital system. The hand off to oblivion problem will also occur with TDMA and GSM digital systems. CDMA has an improved hand off that greatly reduces the problem of being handed off to a full cell site.As of today, no digital system has the coverage provided by analog. Therefore, a dual mode phone (analog and digital) will be more likely to work as you travel from place to place in North America.As far as voice quality is concerned, the issue is a bit more complex. When the analog signal is good, voice qualtiy on an analog phone can be suberb. As you get further from the cell site, the background noise increases and the voice quality degrades. At the fringes, the voice on the other end of the call fades into the background noise. In digital service, voice quality depends on the type of service (TDMA, GSM or CDMA) and to some degree, the number of other users on a cell site. As you move away from a digital cell site, the voice quality remains constant. At the fringes, and this also means inside some buildings, digital systems drop parts of the call. You may lose a few syllables, or entire sentences.I hope that this helps.BHURD
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