Im am using a software called siptosis from mhspot.com. coming directly from my phone adapter all the registration settings have to be turned off. If you look at the site on the setup directions youll see what I mean. when I call from the PBX i get a call failed message on the siptosis and a busy signal on the phone. im gettint the correct reaction from the siptosis, identical to a direct connection from the phone modem, but it still rejects the call. my only though is the pbx is trying to register and im not sure how to prevent that.