How do you use Direct TV without a land line?
Just unplug the land line. The purpose of the land line was to connect and report any programs you had purchased for billing purposes, and it may disable some functions in your receiver if you leave it unplugged for any length of time.
Used to be that the box would store up to 12 movie purchases on PPV, so that if you used your receiver in a mobile home or on the road, it would call in and report them when you got back home, so that you could be billed.
Not too sure how Direct handles things now, but I would imagine that having it unplugged for a short period of time wouldn't pose much of a problem. Best bet is to search on the web for more info on the subject and find out what's going on with them currently.
Hope this helps,