41 lines
2.2 KiB
Markdown
41 lines
2.2 KiB
Markdown
---
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layout: page
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title: "I built my own private telephone network"
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description: "Nobody makes phone calls anymore"
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date: 2022-02-14
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tags: project pbx
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draft: true
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extra:
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uses_katex: false
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auto_center_images: true
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---
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Over the past few months, I have built my own [internet backbone router](/blog/amprnet-bgp) (and an [internet exchange](https://ffixp.net)). So logically, the next step is to branch off into telephony... *right?*
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Eh, even if I never get any practical use out of any of this in the end, at least its content for the blog.
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## A simplistic introduction to telephone networking
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This is all coming from someone that has very little experience with the telephony world, but I *have* managed to make all my gear work, so this can't go too badly.
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As far as I have ever been concerned, the telephone network looks as follows:
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But in reality, it looks a little more like the internet (I guess that makes sense, since dialup was a thing).
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The *Dark Magic* still exists, and I am still not entirely sure whats going on there. Presumably some kind of routing protocols exists to handle country codes and such, but I have had no need (yet) to explore this further.
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Continuing on with terminology, **Phones** are simply endpoints. Such endpoints could be cellphones, VOIP clients, automated answering machines, etc. **Carriers** are the same as the internet world. Big companies that own switching gear and phone number blocks they charge you to connect up to.
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Finally, **PBX**es. A [Private Branch eXchange](https://en.wikipedia.org/wiki/Business_telephone_system#Private_branch_exchange) (PBX) combines the concepts of routers and [NATs](https://en.wikipedia.org/wiki/Network_address_translation) in the telephony world. A PBX can be hardware-controlled, or software-defined through something like [Asterisk](https://en.wikipedia.org/wiki/Asterisk_(PBX)).
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I have personally used Asterisk a fair bit due to its heavy use in the Amateur Radio world as the backbone for repeater interconnections. More on this in a bit.
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## The goals for this project
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