I'll keep my AT&T (now Frontier, whoever in the HELL they are) landline until they pry it from my cold dead (etc.) even though I have an internet phone line on my Comcast modem/router.
As I said to the nice lady in Arizona yesterday as we were troubleshooting my problems: "No, nice lady in Arizona, the number you can call me back on if we get disconnected is a traditional AT&T landline, so you needn't worry about disconnecting me when you try jump-starting this modem again. And might I add, I wouldn't exactly be talking to you and getting help right now if my main line was the internet one, now, would I? Eh? Would I now? Would I?"
(Insert "Would I?" joke here.)
(Of course I also explained that cell reception here at the house is only fair to middling, another perfect reason for keeping the buried phone lines God gave us.)