"It's volts that jolts but it's mills that kills."
I read many years ago that someone was killed by a 28 volt system. One hand on each pole and a a good wet system, and it could be nasty. Unusual in the extreme, though.
The telephone ring signal doesn't provide that sort of current. It'll give you a nasty surprise, but unless you have a weak heart, you'll survive, making a mental note not to do that again.
Under the bench here is a linear amplifier power supply providing 2.5 kV at a maximum current of 1 amp. Touch that, and it's instant harp lessons. It's well fenced in!