Back in the day we were a major Samsung Dealer. Samsung had ring time override (RTO) buttons and ring plan override (RPO).
RTO would keep the system stuck in a certain mode until manually turne...
Many other systems have this feature (grandstream, ecx, others)
I believe it would be down to assigning an optional extension number to the Schedule and add a dial plan. Something like
*887,[Schedule #]
then prompt "Press zero to return to normal schedule, 1 for Open hours, 2 for Closed .
And in the best world it would control the LED. Off = normal, ON= Day, Flashing=Night