Current Thinking for Whole House Paging

OP to be completely honest, I did not read every detail of your posts... But, I did register to this site just so I could share some insight with you. There is a new device, available very soon (1st of the year), that seems to cover almost all of your MUST HAVE requirements above. The requirements in question would mostly fall under the phone category. 
* I am not advertising or selling in any way. However, I just received a hands-on demo of this system today and was impressed. 
Origin Acoustics Valet 4 Zone Amplifier: