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Cisco Networking Simplified, Second Edition by Paul Della Maggiora, Neil Anderson, Jim Doherty

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Part VII. Unified Communications

Unified Communications

Communication on the Data Network

Not too long ago there was a single “network” called the public switched telephone network (PSTN). Of course, this is the worldwide phone system, and for a very long time it was the world’s biggest network. Somewhere along the line, some smart people figured out that by using different frequencies to represent 1s and 0s, computers could communicate. As soon as this technology became popular, the speeds were too slow for big data transfers, so a “data-only” network was created. Then some smart people came along and figured out how to turn the human voice into 1s and 0s, and voilà—we ...

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