What's a Landline?

I was on a work conference call when I heard someone dialing a phone. A few seconds later I realized the girls were dialing the phone. Before I could say anything they seemed to hear us and hung up.
When my call was over I said to them, "You cannot pick up the phone and dial RadioDisney when Mommy is on the phone. All the phones in our house are connected to the same line so when you pick up one while I'm on a conference call everyone on the call can hear you."
They looked at me with wide eyes and said, "They could hear us?" It was the same wide-eyed look they gave me when we were walking through the Wabash County History Museum and I told them operators used to connect phone calls because phones didn't have buttons.
It was at that moment that I realized they didn't know one landline connected all the phones in the house. In their world Mommy and Daddy each have a phone and can call each other on those phones. Of course all portable phones would work the same way.
I explained the difference between our mobile devices and the house phones. They nodded seriously and went back to play. I sat for a moment and realized that by the time they grow up and get a house they probably won't even have a landline. Some day they will tell their children the story and it will be like their parents were part of some magical ancient time when people had landlines and telephones connected to a wall. Their children will look at the wide-eyed and ask questions about the good old days, just like our girls look at me now.