Kids with cell phones?

Ok so hear me out a little…

Anyone here watch the movie The Holiday?.. you know the scene where Graham (Jude Law) is at his sisters house with Amanda (Cameron Diaz) and his phone rings and it’s one of his two girls (Sophie and Olivia). Well Amanda sees the phone and sees one of the girls’ names. Then the phone rings again and it’s the other. This would imply they have their own caller ID… how would that be unless they each had their own phone?? (Or did I remember this scene completely wrong)

The reason I bring this up is because the same thing happened on Bones with Christine calling her mom. Brennen is in the lab and she sees her phone and says something like ‘oh it’s Christine’ …

Are we just all assuming everyone has their own phones?.. I mean The Holiday came out in 2006!

Maybe I’m just old because I grew up with only land lines and cell phones weren’t even common place till I was an adult but still… anyone else think about this?