Tell us about yourself!
The static electricity that zaps you when you walk along the carpet... is quite a bit higher than 50volts. I believe in the thousands!? It is the current that is dangerous. I've zapped myself on household current (thankfully not thru the heart) and been fine. A DC source will lock your body in a clench. AC can get you to lurch which could release the offending conductor.This is of course not a good thing to do regularly... Interestingly enough the phone station uses batteries in a power outage. Then maybe generators after a bit.We were told in training that it wasn't really bad to work on the wires while plugged in, but I get the feeling we should have.If you wire it and insulate it properly then plug it in you'll be fine.
From my memory, the ring is about 90volt ac at I don't know what frequency. Make sure that you have a current limiting power supply(set to a very small current) so you don't melt something. An inverter and a few solid state voltage increasers... I don't know what they are called... Or the inverter with transformers should work from a battery.