Telephony has come a long way.
It used to be that a PBX cost thousands of dollars and required staff to set up and manage it.
Now, all it takes is a PC, a connection to an ISP and a SIP service provider (along with some free software) and you're up and running.
Right... That's all it takes... Should be a half-hour's work...
OK - I've heard this kind of thing before - and I've learned that whenever someone starts a sentence with "It's really very easy. All you have to do is...", they've:
A.) overestimated my ability;
B.) read about it but have never actually done it;
C.) already mastered the subject in question and forgotten what it's like starting at the beginning.
I'll be starting this project using an easy-to-use version of Asterisk (PIAF) on an old PC running CentOS (a version of Linux) and reporting on my progress here.