Do I have to have a landline?

[Lord Darth Vader]

With NFL Sunday Ticket, yes you need it.

No you don't.

 

[talos4]

Just a heads up but if you also have cable internet and use a voip phone service like Vonage you can connect a phone jack via the adapter and it works just like a landline without having a landline because thats what I use.

Same here, TWC gave me the usual warnings about VOIP not being able to connect to equipment with a dial up modem, I've been using mine for about 4 years without an issue.