wip telephone post

content/blog/2022-02-14-personal-pbx.md

@@ -3,8 +3,38 @@ layout: page
 title: "I built my own private telephone network" 
 description: "Nobody makes phone calls anymore"
 date:   2022-02-14
-tags: random 3d-pipeline
+tags: project pbx
 draft: true
 extra:
   uses_katex: false
+  auto_center_images: true
 ---
+
+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?*
+
+Eh, even if I never get any practical use out of any of this in the end, at least its content for the blog.
+
+## A simplistic introduction to telephone networking
+
+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.
+
+As far as I have ever been concerned, the telephone network looks as follows:
+
+![The magical phone network](/images/posts/personal-pbx/magic_phones.png)
+
+But in reality, it looks a little more like the internet (I guess that makes sense, since dialup was a thing).
+
+![The magical phone network, with more phones](/images/posts/personal-pbx/phone_internet.png)
+
+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.
+
+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. 
+
+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)).
+
+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.
+
+## The goals for this project
+
+
+

static/images/posts/personal-pbx/magic_phones.dot

@@ -0,0 +1,7 @@
+digraph G {
+    rankdir=LR;
+    client -> magic -> client2; 
+    client[label="Phone A"];
+    magic[label="Dark Magic"];
+    client2[label="Phone B"];
+}

static/images/posts/personal-pbx/phone_internet.dot

@@ -0,0 +1,38 @@
+graph G {
+    rankdir=LR;
+    
+    client1 -- pbx1;
+    client2 -- pbx1;
+    
+    client3 -- pbx2, pbx1;
+    client4 -- pbx2;
+    
+    pbx1 -- carrier1;
+    pbx2 -- carrier1;
+    
+    carrier1 -- magic;
+    magic -- carrier2;
+    
+    carrier2 -- client5;
+    carrier2 -- pbx3;
+    
+    pbx3 -- client6;
+    pbx3 -- client7;
+    
+    client1 [label="Phone A"];
+    client2 [label="Phone B"];
+    client3 [label="Phone C"];
+    client4 [label="Phone D"];
+    client5 [label="Phone E"];
+    client6 [label="Phone F"];
+    client7 [label="Phone G"];
+    
+    carrier1 [label="Carrier A"];
+    carrier2 [label="Carrier B"];
+    
+    magic [label="Dark Magic"];
+    
+    pbx1 [label="PBX A"];
+    pbx2 [label="PBX B"];
+    pbx3 [label="PBX C"];
+}

templates/page.html

@@ -42,6 +42,19 @@ MathJax.Hub.Config({tex2jax: {inlineMath: [['$','$'], ['\\(','\\)']], displayMat
         }]
     }
 </script>
+
+
+
+{# Handle auto-centering request #}
+{% if page.extra.auto_center_images %}
+<style>
+    img {
+        display: block;
+        margin-left: auto;
+        margin-right: auto;
+    }
+</style>
+{% endif %}
 {% endblock head %}
 
 {% block profile %}

templates/section.html

@@ -54,7 +54,8 @@
 <ul>
   {% for page in section.pages %}
   {% if not page.extra.hidden %}
-    <li class="blog-post-li"><a href="{{page.path}}">{{page.title}}</a> <span style="color:{%if page.draft%}red{%else%}gray{%endif%};">({{page.date}})</span>
+  <li class="blog-post-li"><a href="{{page.path}}">{{page.title}}</a> <span
+      style="color:{%if page.draft%}red{%else%}gray{%endif%};">({{page.date}})</span>
   </li>
   {% endif %}
   {% endfor %}