FWIW, some tidbits from the HR20 segment, apparently, if the customer has HDMI available, it is MANDATORY (their own words) the installer use it, with the installer providing the cable, otherwise, the installer is to use the best quality connection possible, with cables provided.
It then says that a phone line is required (as always), but this time, it states that future (inter)Active functions will depend on the line being connected, and that without a line, such functions will not work, it does not elaborate further.