Before we start talking about a RG do you know what kind of install you are having done? If you are a long distance from the cross box you may be getting an iNID and a different inside unit.
In this case the TV would be run with coax to the diplexer. Phone will also be tied in to this outside box.
Inside you will have you inside unit which the computers hook up to (this unit is ran over a single pair of phone cables to the outside unit) and a power supply with a backup battery run to the outside unit.