One of the most searched topics in the is how to change the ringtone. You will find two sets of DIP switches inside the monitor casing.
Some versions have a jumper to split or join the ground (Terminals 6 and 10). If the door lock doesn't trigger, check if this bridge is needed. Volume Adjustment:
Do not short-circuit A and B. Do not apply 230V AC to these terminals. The system works on 32V DC.