Hello.
The old telephone amplifiers were neat but serve no purpose now.
The old scheme had a multi-party line, one pair that ran to all the houses.
To provide more than one path and to improve voice quality the phone company provided amplifiers.
The things could provide a second or 3rd circuit by providing a carrier channel much like DSL works now.
And they evolved, it was not all that uncommon to see one built in the late 30s with a solid state circuit board under the chassis and the 3 tubes changed to solid state plug in units.
As time went on features were added all the while leaving the basic design intact.
Sometimes the phone company would do a major upgrade and simply leave the old box unplugged.
Since most people have not a clue they are left there.
But what you will be looking for is the older farmhouse that was in the country at one time.