I am hardly an expert myself but these two resources helped me build a bit of intuition: - The route of a text message: https://scottbot.net/the-route-of-a-tex

I am hardly an expert myself but these two resources helped me build a bit of intuition: - The route of a text message: https://scottbot.net/the-route-of-a-text-message/ https://scottbot.net/the-route-of-a-text-message/ - Architecture of Asterisk - http://aosabook.org/en/asterisk.html http://aosabook.org/en/asterisk.html