Where to Measure Voltages?

[dsk]

It is actually made European and international standards for Ringer loads, but again they are not of much use for us.  A modern ATA will in real life ring a modern electronic ringer of an impedance of 16000 ohms at 20-60hz and put out at least 50V AC with no specifications of wave form. Usually the have no problem of ringing an old phone, or maybe more, and usually the use a frequency of 20-25Hz.  Les and less have the tradidtional POTS, and the ringing signal may be less strong than before, so if we want many phones on a line, we just have to try it out.

[markosjal]

I think that if you look at most "REN" stickers on phones in the USA, they usually refer to "FCC REN" if I recall correctly.