It doesn't extend at all, thats why he was confused. Basically any Wifi in your home has the same range as your cordless phone. When you get Cox service what your getting is the internet service coming through the cable wire, into your house, and into your cable modem. The range at that point depends on what kind of wireless (Wifi) router you have connected to the modem. Just like the range of a cordless phone depends on the phone. Certainly not in another state though.
You would need to ask the person/place your staying and see if they have internet and/or wifi.