All those receivers are hooked together to a central located SWiM switch with coax right? well that coax is capable of 2 way communications on any frequency, thus it is able to transfer data from the phone line to other receivers off the splitter. Not an expert DTV guy but just makes sense to me. Dish has the same setup, all VIP rec's only 1 needs a phone line connected. They also use the 2 way ability by diplexing an analog signal backwards through a forward feeding digital signal from the dish to IRD. Good luck.
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