How to set up asterisk addon?

How would one set-up the asterisk addon in home assistant? And how would one aquire a free phone number and service that allows incoming, and outgoing calls, and has caller id? I want to try to get it setup so I can place free calls as a backup phone line, I have an obihai 302 adapter I want to try to connect to the asterisk server with sip, and not sure exactly where to start with this. I Installed the asterisk addon.