DIY phone intercom with ringer without local power.?

I want to put a simple phone intercom between the garage and the dock at my cabin. I have seen videos and diagrams for using old landline phones as a "hot line" triggering a external ringer on phone A when the receiver of phone B is simply picked up (and vise a versa) but in order to ring a 9v battery is... show more I want to put a simple phone intercom between the garage and the dock at my cabin. I have seen videos and diagrams for using old landline phones as a "hot line" triggering a external ringer on phone A when the receiver of phone B is simply picked up (and vise a versa) but in order to ring a 9v battery is needed at each phone. I'd rather not have to replace batteries, rather use regular wall outlet power. However, the dock doesn't have it's own power. I know that normally when the phone is connected to the wall jack it gets its power from the phone line, similar to Power Over Ethernet (POE). Is there a way to wire the phone line so that the power in the garage is used to activate the phone's built in ringer at the dock?
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