Skype has released version 1.3 of its VoIP and instant messaging client software for Windows XP and Windows 2000.

The software features the first official version of the Skype Voicemail service that has previously been in beta. The application lets users leave a voicemail message for a Skype account, similar to a telephone voicemail.

It is the second of Skype's premium services to go live, and the package costs €5 for three months or €15 a year. The Skype Voicemail beta service has more than 40,000 users, a Skype spokeswoman told vnunet.com.

"We expand Skype's benefits to users and deliver more potential in modern communication and collaboration," said Niklas Zennström, Skype's co-founder and chief executive. 

The company launched its first premium service last year with SkypeOut, which lets users make low cost phone calls from their computer or Skype-enabled handset to a regular telephone number.

A beta version for a third premium service, called SkypeIn, was launched simultaneously with Skype Voicemail last April, but remains in the testing stage for now. 

The service assigns a telephone number to a Skype account, allowing outside users to contact them through their phones. The plan charges users €10 for three months or €30 per year, which includes voicemail.

Taking the guesswork out of finding out who else has signed up for the service, the software now includes a feature that checks a user's address book against the full database of Skype users. The software looks for matches in the email address book in Microsoft Outlook or the MSN software.

Previous versions of the software required users manually to enter and look for contacts that had registered for a Skype account.

Skype plans to add support for additional desktop applications in the future, according to the spokeswoman. She declined to provide any titles.

Users looking for an ever greater level of integration between Outlook and Skype can purchase the Outlook2Skype plug-in from ExchangeWise, which lets users place Skype calls to both Skype users and telephone numbers directly from Outlook. 

Skype manages one of the world's largest VoIP networks. Founded by the creators of the Kazaa file sharing software, the service boasts 42 million registered users and claims to be growing at a rate of 150,000 a day.