IP telephony firm Skype today claimed that its software has been downloaded by over 100 million computer users. To mark the occasion the company has launched two premium services.

Skype said that 35 million registered users have now used its software to make over seven billion minutes of voice calls. Customers are able to make free phone calls among themselves using voice over IP technology and a standard internet connection.

Skype chief executive and co-founder Niklas Zennström attributed the success of the software to the "viral power of our user base".

"Skype is simple to use and easy to share, and the marketplace is responding by making it its first choice in internet telephony," he said.

The two new services are SkypeIn and Skype Voicemail. SkypeIn customers choose a country and area code and are assigned a standard telephone number. Anyone may call the SkypeIn user's SkypeIn number wherever the user travels, and no international roaming charges are incurred.

SkypeIn users may purchase up to three numbers from their home country in Denmark, Finland, France, Hong Kong, Sweden, the UK and the US during the beta period.

Skype Voicemail allows users to store messages up to 10 minutes long and record their own greetings.

SkypeIn ($39 a year) and Skype Voicemail (free with SkypeIn service or $19 annually) are currently in public beta, and software is available for Linux, Mac OS X, Pocket PC and Windows.

The basic Skype software can be downloaded here.