On Tuesday, January 21, 2020 at 7:26:22 AM UTC-5,

Hi, I saw that "sandman", and other places on the web, but it did NOT say
anything about the ringing voltages from red to ground or green to ground..

That is why I made this post.

a) Most POTS phones are two-wire these days.
b) In most cases, the ground (separate) does not leave the demarc.
c) Both the the "red" and the "green" are not at ground potential, *and* also not at the same potential to each other.

Therefore the 'ring voltage' will be different from each to ground than between the POTS conductors. Which was covered in the article linked, but not with these same words. Read carefully the section on measuring AC over DC, and that should help you understand.

Peter Wieck
Melrose Park, PA