If anyone is interested, I go through my steps of creating a custom component for HA. In this case it is a custom sensor that monitors my voip phones on my Asterisk server. It can be found here.
The project ends up with an automation that flash my Philips Hue lightbulbs when I receive a phone call.
https://www.cron.dk/asterisk-in-home-assistant-part1/
https://www.cron.dk/asterisk-in-home-assistant-part2/
https://www.cron.dk/asterisk-in-home-assistant-part3
Comments are welcome 
Best regards,
Alex