RADIOTELEPHONE In addition to the wireline telephones described in The telephone instrument , there exist a number of wireless instruments that are connected to the public switched telephone network (PSTN). At the present time, these wireless telephones generally fall into one of three categories: cordless telephones, cellular radio systems, or personal communication systems. Eventually these systems will be expanded to include global satellite-based telephony. Cordless telephones. Cordless telephones are devices that take the place of a …
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showed last 75 words of 2349 total
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