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.

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.

People need to access Skype wirelessly, no matter where they are, and what happens is that we'll be taking advantage of the rollout of Internet everywhere - WiFi and WiMax in particular.

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.

Silicon Valley is the best place to start a tech company in so many ways.

It's extremely hard to build a company with a product that everyone loves, is free and has no business model, and then to innovate a business model. I did that with Kazaa, had half a billion downloads but that wasn't a sustainable business.

They also can combine voice with instant messaging and online file sharing.