I've had a lot of PPV problems with two Directv units.
In my conversations with Directv about the ongoing problem, they indicated the units are supposed to call Directv once a month with PPV information.
Mine weren't, and I'd have to call Directv and have them send down a signal to 'kickstart' them and have them call in before I could order.
A month later they were supposed to call in but hadn't and I'd have to call again before I could order.
It could be the phone line. I don't know. I gave up on using PPV. I've seen threads about the problem.
One of them is a Directv with TIVO and TIVO calls in every day.