Is there a free PBX for Windows?

Question

Telephony

Can you please tell me if there is a free PBX for Windows for 10 users? With two simultaneous calls.
In general, under Windows I did not find PBX except 3CX, but they have very limited functionality with a demo version.
Of course, I saw AsteriskWIN32, FreeSWITCH and others that are issued by Google, but there is no convenience, the same command line and we write everything with pens.
Very interesting version of Ozeki pbx, excellent configuration panel, full functionality. But in the price list they have this for the minimum version: 8 outside lines, 15 simultaneous calls, 15 SMS per minute
I wonder if a smaller number of users can use it for free. The server was installed freely.

Answer 1

Why doesn't 3CX fit?
There, it seems, using a demo key, you can open commercial functionality for 2 simultaneous calls.

Answer 2

FreeSWITCH