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

In old fashioned telephones with actual bells in them, the phone line would send 60-100 volts on the “ring” wire to directly power the bell. Modern electronic and cordless phones instead just have a CPU input to *detect* that voltage, and they play their electronic ringtone in response.