Quote
An analog telephone line is nothing more than a 600-ohm balanced line...


Well, I wouldn't believe everything the rocket scientists put on the internet. It may be a 600 ohm line BUT there are other things going on like battery voltage, supervision and ringing. So it's certainly not just a 600 ohm balanced line as used for audio.

-Hal


CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.