Comcast and the others did compete against T and VZ with wireless. Although they choose to use resold Sprint services and thus fast higher packages due to sprint having to get their cut. Nobody knew anything about the services; you couldn't move a current Sprint phone to Privit (the cable side) and if you could; you had to jump through hoops to find someone that knew what they were doing.
Sprint is a MAJOR provider of the Digital Phone side for the MSOs. They provide a great deal of the DIDs and the backend without much effort from the MSO. TWC's major partner is Sprint for this.