Tivo Suing More Operators That Use DVRs

Suing Dish for it's DVR isn't enough for Tivo; add AT&T and Verizon to the list. "TiVo's complaints, filed in the U.S. District Court for the Eastern District of Texas, claim that the telephone companies infringed upon its Multimedia Time Warping System, its System for Time Shifting Multimedia Content Streams, and its Automatic Playback Overshoot Correction System when they deployed their own DVRs." So why are the cable companies not being sued. Are their DVRs made up differently. Certainly they wouldn't sue Comcast as a distribution deal is in place, but what about the others? As the Dish lawsuit has been going on for years, these should take just as long.