”The voltage at the subscribers end depends upon loop length and number of ringers attached to the line; it could be between 40 and 150 Volts.”
I think they also (relatively to the hardware in a VoIP adapter) need a large amount of power.
So, to ring that bell, you need to transform your 5V/3V/…, and you need a larger power circuit. That isn’t worth it for the few who still have an old-style telephone.
https://www.epanorama.net/circuits/telephone_ringer.html:
”The voltage at the subscribers end depends upon loop length and number of ringers attached to the line; it could be between 40 and 150 Volts.”
I think they also (relatively to the hardware in a VoIP adapter) need a large amount of power.
So, to ring that bell, you need to transform your 5V/3V/…, and you need a larger power circuit. That isn’t worth it for the few who still have an old-style telephone.