LONDON, England (CNN) -- Swedish software guru Niklas Zennstrom co-founded Skype, a pioneering voice over Internet Protocol (VoIP) company. Here he talks to CNN's Charles Hodson about his software, which allows Internet users to make free PC-to-PC phone calls to anyone in the world.

Hodson: What is Skype and how does it work?

Zennstrom: Skype is a software that anyone can download through their computer or PDA. With this software they can make free unlimited crystal clear telephone calls over the Internet.

Hodson: It sounds as if you're going to replace the traditional phone company. Is that what you plan?

Zennstrom: Over a long period of time I believe the majority of voice calls will go over the Internet, and Skype hopes to be leading that way. But, just as the e-mail did not replace the fax, and the fax did not replace the post office, I'm sure the phone company is still going to be around.

Hodson: How many people have actually downloaded this software or have got hold of it in some way?

Zennstrom: We have 11 million registered users. We have been producing over 1.5 billion minutes of calls between Skype users.

Hodson: And how do you see that growing?

Zennstrom: It grows exponentially. Today we have 70,000 new users a day. In May we had 30,000 new users a day. In January we had 15,000 new users a day, so it's exponential growth. Every four months we're doubling the number of users.

Hodson: You're taking on the big established industry and trying to introduce a degree of change and presumably along the line some profits for yourselves?

Zennstrom: Absolutely. It's all about disruptive technologies, which creates opportunities. And much better solutions for consumers, and anyone actually in the industry, and what we're able to do here to utilize the fact that the infrastructure is in place. The broadband Internet is in place. What we're doing is we've created some software and that makes it very easy for people to connect and talk to each other, exchange files and whatever they want to do. That makes it much more efficient for us to make a call with Skype. The marginal cost we have to produce the call is zero.

Hodson: So what's next, both in terms of the way you develop your technology and your business?

Zennstrom: What we will continue to do is to expand the number of users using Skype because this is a network and the more people connected to Skype network, the more powerful it becomes. So one focus is just to continue to grow. The other focus is to make it available on other platforms -- specifically mobile platforms -- and what you see now what's happening is that you have mobile phones or PDAs which are all converging into the same type of technology and they're connected to WiFi networks and 3G data networks, which is also another form of broadband and you'll see Skype available on these mobile devices. Most importantly, though, is to keep everything very simple because, although we're in the business of developing advanced technology, we cannot lose sight of what this is all about. And that's making simple technology for consumers and businesses so we have to focus on making it really, really simple to use.


D, world destruction
Over and overture
N, do I need
Apostrophe T, need this torture?-They Might Be Giants