The room number you planned.
⚫ If you use multiple indoor monitors (VTH), the room
number of the master indoor monitor (VTH) should be
"room number#0", and the room number of the extension
VTH should be "room number#1", "room number#2", and
so on.
⚫ You can have 9 extension indoor monitors (VTH) at most
for one master indoor monitor (VTH).