I am using a kxtda15 system to which is connected a Kxt7630.i have a slave 7630 connected to this. The slave 7630 is working fine. It can make calls and ring other extensions. It is connected to ext 21.When I use its own keys to identify its extension number it shows 10117 but I'm not allowed cal that number.Can anyone help me identify the extension number of the slave Dpt please? Many thanks.