I have had a cellphone for 3 years now and I have amassed a total of 100 hours used (dialing and receiving calls). On the other hand, my daughter has hit 100 hours in less than 2 weeks. I don't bring it to work because I can't get a signal (my office is inside of a building which is inside of a building).
Oh, and I also use it as a clock when I need to know what time it is.
