Why?

[Jimbo]

May I point out that traditional landline is a subset of landline. Traditional landline is copper based. Landline includes not only that but also VOIP. It could turn out that both of you have a sense of correctness in your posts.

FWIW - I have both a copper based landline and a VOIP landline (as well as two cellphones) in my household.

Technically, I don't consider VOIP to be a Landline ... then again, it's not Cell Phone either, but it Is Internet.