Flunking Sainthood - week 3

I've been thinking about the boundary between needs and wants - and when it is that things make the jump from one to the other.

We can all agree on the basics - I think - food, shelter, water, clothing.  Those are all needs for everybody at all times and in all places.

But it gets more difficult as we think about specific cases.  For example, it would be hard to argue that some kind of a telephone is not a need in 21st century America.  While a car may not be a need in New York City or Chicago - it kind of is in Clarence.  I guess it's technically possible to get around without one - but it's so difficult as to be unrealistic.

So what about voicemail? a computer? a t.v.? a radio?  Which of those things are now, in effect needs?  When does something make the jump from a want to a need?  What are the criteria?