I have a valcom 2003a which I have 3 zones set up on. I also have a 909a coupler set up. I am not sure how everything is supposed to work...........so it is tough trouble shooting. Can someone tell me how the AUX ports work ex. where the voltage comes from where is it supposed to go as far as the coupler is concerned. And just basic tips on how to trouble shoot the system. I have already replaced the valcom 2003a and all zones still do not page. Looking at replacing the coupler but not sure how to make certian it is bad.