I think one of the many lessons for the telecom industry from the advent of Skype has been the need to redefine our understanding of user motivation. Obviously, the industry was right to be alarmed (when it would admit to being alarmed, that is) at Skype's potential to drive simple price arbitrage opportunities, but there was clearly a lot more going on than this alone. Ease-of-use, audio quality, presence, multi-chat, file transfer, etc., all came together to form a "killer cocktail" experience for the user, resulting in something not necessarily recognisable to the industry as a competing "voice service". It was/is something else, another behavior - purple minutes vs. grey minutes, as JP might say.
This view seems to be borne out by a survey just out in Japan (Japanese only, ご免ね、外人さん). Japan.Internet.com and goo Research interviewed 1,011 internet users aged 20 - 59, and found that just over 11% of them (113 people) had downloaded and installed Skype, and 42% had heard of it. Of those who hadn't used Skype, once the application was explained to them, just over 42% expressed some degree of interest in using it. What I find most interesting and relevant is that, of those who had installed Skype, only 14% said that their use of fixed line and mobile phones had declined as a result, in contrast to 74% who said that their phone usage patterns remained unchanged. This is consistent with a similar survey carried out among Skype users last year, which found that 20% said their conventional phone usage had declined, while 78% cited no change.