Well the sd1 doesn't respond to the panel, so what you on about dude
Example if the sd1 is connected to the bell output of the panel in trigger , bell activates , triggers dialler , dialler dials , person responds pressing 8 dialler either stops or calls next number if it's setup to call next number
Maybe dialler has lost some settings somehow and you need to reprogramme
Maybe explain what you mean by control panel is not responding