I haven't had a landline for almost 10 years. There are a variety of reasons, chief being that I've been technically homeless and/or living on the road for large chunks of that time. Since getting jobs is a lot easier when people can call you, I've kept a cell phone the entire time. My current is an average smart phone, which costs me $40 a month for unlimited talk, text and data.
I don't find it necessary to leave my phone at home in order to ignore it. I'm quite capable of doing so either intentionally or unintentionally.