I have one tivo box connected to my phone line, but the other tivo box in another room is not connected and works just fine. My daughter doesn’t have her tivo box connected to the phone line either in her house. She didn’t tell Direct TV about it and it works fine also.
I'm beginning to get po'd with my cable company (Brighthouse) as they have few HD channels and the few you can get in addition to the broadcast networks don't belong to a tier but in their own HD package.