Cell, Land Line or Both?

When I was getting ready for bed Thursday night, I checked the power on my cell phone, as I often do. I happened to notice I missed a call from my friend. I had spoken to her fifteen minutes before, but she got another call and was going to call back. In the meantime, she called my landline. I had wondered at the time why she did that, but didn't ask.

Apparently the call to my cell didn't go through, or maybe I just didn't hear it with the TV on.
It's a good thing I have both kinds of phones.

What about you? Do you use a cell, land line or both? Which do you like better, or does it depend? Please share.