"Ye Olde" phone line, as a charger!!!

[Ah-Those-Old-Days!]

Do you suffer from power failures often, or are in an area/place where there is *generally* no A/C power, but there IS a phone-line???
The *phone-Line* generally supplies ABOUT 48v DC, even when there is a power failure!! Of course, that changes when the 'line' is 'Ringing'
etc., (various A/C voltages) and when talking. There are various *simple* circuits though, that allow one to use that Phone-Line to for instance
charge your USB powered SmartPhone!!... As per this following link...

Mind you, I do not know (yet?) how/if this would work via the new NBN/Broadband Network connections??
P.S. I don't know if there is enough 'power' for the likes of an 'iPad' etc???