VOIP is nice, but I don't really need an outside line. I am just looking at say making calls from the bedroom to the basement, or call from the kitchen to the garage (Honey, dinner's ready!) Part of this too is that I have some old Western electric phones that I want to "show off" to visitors...you know, the kind with real bells in them
I've found many old office PBX boxes out there of various types...The AT&T merlin systems can be had a dime a dozen, along with many others, as offices move to VOIP, but the problem with using one of them is that they require proprietary phones. That looks like a fun little project that he's put together there, and it works with regular phones too!
I'm just real surprised nobody builds, or at least I have never found one, a telephone box that allows one to put together a small private telephone network.
Years ago, I remember a family friend had two old crank telephones connected together. One was at his grandmother's house on the other side of the farm, and he had the other one. It had a big battery that sat on the floor. If you wanted to call grandma, you picked up the earpiece and turned the crank. Her phone would ring when you turned the crank and she would answer
It was their own "hotline". The cable was strung along the fence around the field...about 800 feet of wire or so between the two houses!