reported that the Nokia 1100 has sold 200 million units. The phone
sports the "Navi Key" interface style developed in 1996/97 by a team led by
Christian Lindholm. This single softkey interface works amazingly well and
apparently still do.
With the other "Navi Key" models, a fair guesstimate would be that 500+
million devices with this user interface has been sold.
I think this is a good example of how interaction design actually made all
the difference in a product that became a runaway success world wide.