- Jan 1, 1970
The polarity doesn't change for the duration of the call, but it does
after the far end hangs up. Its called reverse answer supervision. When
you call and an answering machine answers - and then you hangup, the
Central Office momentarily reverses the polarity back towards the called
party and the answering machine knows to hang up.
Where is this feature available (country, telco name) and what is its name?