Another differentiator is that Skype is free and simple to set up, and it costs us virtually nothing for a new user to join the Skype network, which is why we can offer the service for free.

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

When we look at investing, we always think about 'how defensible is this, how likely is it that somebody is going to copy this.' E-commerce tends to be something easy to copy because it's execution.

Skype is easy enough to use so that people don't need to be tech savvy - a lot of users just want to communicate with their friends and family, and they find this is the easiest, cheapest way.

Another differentiator is that Skype is free and simple to set up, and it costs us virtually nothing for a new user to join the Skype network, which is why we can offer the service for free.

Talent can pop up anywhere in the world, it's not just one city block.

Surround yourself with smart, dedicated people - to build something isn't a one-man show. It's more important to have smart people who really believe in what you're doing than really experienced people who may not share your dream.