Viking DLE-200B Two-Way Line Simulator

Honestly, Phone simulators exist, kind of pricey but you hook up two phones and lifting one handset causes the other to ring. pretty cool. https://www.amazon.com/Viking-DLE-200B-Two-Way-Line-Simulator/dp/B004PXK314 Edit: Ha, someone beat me to it. Also things like Magic jack exist. I used to use a duo connect, but they went all virtual. other services have the same. Look up SIP providers. https://www.3cx.com/partners/sip-trunks/Adapters fora single phone aren't that bad.

Jeff Geerling made a video about something similar. He mentioned this device. https://a.co/d/0gCvsNC0 Network Chuck has also posted similar videos in the past setting up traditional phone systems.