Packet Data Systems
While Internet access via a mobile phone is hyped, there are already several data-only cellular systems. Though none offer the capacity needed for full-scale Web surfing, they are used for simple messaging and telemetry applications.
The most well known data systems are pagers, which have traditionally carried information in only one direction. The first were known as numeric, because they handled only the digits 0 through 9. They were intended to be used for phone numbers, the idea being that someone who was paged could find a payphone and call the number. Modern pagers are nearly all alphanumeric, meaning that in addition to numbers, they can display letters of the alphabet, and some include many different character sets. ...
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