Lines in Business Telephone Systems

So I'm not sure how many telephone lines a single central office does, but it's quite a few. So let's say Baltimore may have five central offices. A single county might have a central office. What the central office is every single house that has a telephone line in it. That telephone line that is sitting in that house, that little jack you have in the wall, that actually runs all the way back to the central office. So the wire that's in your wall goes out to what's called the demarc point in the back of your house. It goes into that demarc and then basically the same wire runs up to the business phone systems and then on the telephone pole, that wire runs all the way back to the central office, so basically you have a connection, a solid connection all the way from your house or your building all the way back to the central office. That's how that works.

Then what happens, is the PSTN is then the network of these central offices.

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