I would expect that the lower-shelf would be way younger than 25. College students living in apartments probably do not have landlines (I didn't when I was in s

I would expect that the lower-shelf would be way younger than 25. College students living in apartments probably do not have landlines (I didn't when I was in school). Maybe one contributing factor to it starting at 25 and not say, 21, is that in this economy many college grads are moving back in with their parents who have land lines. College students who have stable jobs and are out on their own two feet (a little bit older on average?) choose not to buy into the landline like their parents continue to do.