I have a fresh installed Ubuntu Server machine. I'll provide SSH access.
I want you to install there a FreePBX and configure it in a VERY simple manner:
-Create three extensions 101, 102, 103. Extensions can call eachother
-One TRUNK registered to a voip carrier that can make a receive calls
-Setup outboud rule so that only Italian local calls can be made (+39 country code) and refuse any international call (refuse any dialled number with 00 at the beginning)
-Setup inboud routes base on weekday and time.
-From Monday to Friday, from 9:00 AM to 1 PM and From 14PM to 18PM all extensions will ring at the same time.
-On Saturdays ans Sundays and outside the previous mentioned times, any icoming call will be redirected to an external landline number
-In case of no answer or no extensions are registed on the PBX, any icoming call will be redirected to an external landline number
In case the first landine number will not answer, the incoming call will be redirected to a second landiline number
Incoming calls, when waiting to be connected to an operator, will have to hear a music.