eli5: How do cordless phones detect ringing on the phone line?

Question

How does the base unit’s processor detect ringing from the phone line and ring itself and the connected handsets?

In: Other

Answer 1

Voltage over the line at the most basic level for a land line. At 20 hz sinewave is sent over one of the wires.

Don’t even need a processor to detect that (although a cordless will have one, or possibly a microcontroller serving as one), you can do it electronechanically.