Intro
This is Eloy's website, trying to document some information on retro telecom stuff.
Git repo here: https://codeberg.org/eloy/telco-book
This was partly inspired by the guide from Doge Microsystems. If you want to replicate something like this yourself I can recommend this guide, because it uses parts that are more easily available. I got quite lucky with the modem bank I received from a museum collection.
Also good guide by Marrold: https://www.marrold.co.uk/2022/04/creating-your-very-own-56k-dial-up.html
More: http://robertmartinwhite.blogspot.com/2017/09/using-cisco-vg224-analog-voice-gateway.html
https://github.com/ssshake/retro-computing-internet-resources
PBX by Hans Gelke: https://media.ccc.de/v/37c3-11716-analog_rotary_phones_get_a_second_life_with_raspberry_pi
repo: https://github.com/hansgelke/retro_v3