I'm not sure about the DSS sattelites and when they dial out, I've had one for several years and I have never heard mine dial out. They may have a sensing circuit that tell them not dial when someone is on the phone and with you having single line sets and the partner on the line, the current may be low enough that the DSS does'nt realize you are on the phone and tries to dial out over you. That's just a shot in the dark though.
