IP PBX support

Since the HASS host is also connected to the same network as my IP PBX system, it would be great if I can create an extension for the host so that I can dial in using my mobile phone or any telephone (in case the internet is down) to control the home (example; to deactivate the alarm) via the voice menu (for example; “please key in the pin number follow by the hash key to deactivate the alarm”).

I am assuming Asterisk.

Couldn’t you do that with Home Assistant’s RESTful API?

You have cURL installed in your Linux machine, right? Is cURL compiled into Asterisk?