Could this idea be used, for example, to power a landline phone like it was done with POTS? So no external power was needed for the phone and it even worked in the event of a blackout.
> the average DC current in the loop and voltage across the phone will be up to 42 mA at 12.5 V (short line), up to 33.5 mA at 10 V, and will be not less than 25 mA at 9 V.
So it's around the same values. However the distances are in a different realm entirely: the spec sheet tests over 30m of fiber, phone loops range in kilometers.
