It is very similar to companies like Google and other internet companies. When you go and search on Google you don't pay for that. But sometimes you click on an advert and Google makes money on that.

When we started Skype, if you look at analyst reports, no one forecasted it as a big business. Also when Google started, it was not fashionable to be in search. It's not trying to do the obvious - that's the hard part.

When radio stations started playing music the record companies started suing radio stations. They thought now that people could listen to music for free, who would want to buy a record in a record shop? But I think we all agree that radio stations are good stuff.

Then people started using it more and more and it became the most downloaded software on the internet.

Look for when the environment is changing - the big shift now is mobile Internet. It's really happening big-time. The way you interact with services on a smart phone compared to the Web is quite different, so there's a huge opportunity.

If you can use a Web browser, you can use Skype.