16.1. What's a WAN?
As local area networks (LANs) grew and developed, it became necessary to be able to connect their resources together over long distances—not just locally. At first, we achieved this goal via the phone company network known as the Public Switched Telephone Network (PSTN). And so, the first successful network that could establish voice communications over disparate locations was born.
Because few of us remember back to a time when there was no such thing as phone service, PSTN was an obvious solution because it was already a fully operational circuit-switching network, where every phone call established a unique circuit from one endpoint (phone) to another through a path of switches. So, instead of reinventing the wheel to ...
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