Advertising will initially be limited to one 'sponsor' brand per day. Skype 'Home' provides a sponsored large masthead space at 650 x 170 pixels expandable to 650 x 340 pixels for advertisers to display ads that can include audio or video. The first advertisers to sign up are Groupon, Nokia, Universal Pictures and Visa.

Also, ads will initially appear only for users the UK, US and Germany. Skype has contracted Meebo in the US, Ad2One in the UK, and Ströer Interactive in Germany to sell advertising for Skype in each of their respective markets.

Andy Sims, director of advertising for Skype, said: "All three partners are leaders in their space, have deep relationships with top advertisers and agencies in their markets, and have experience selling high-impact brand advertising."

Skype points out that, since the ads are on Skype, advertisers can add a click & call button in the ad when another call to action. "In addition, it allows people to share the ad to their Facebook or Twitter accounts, and with one-click, ads can also be closed with the 'Close Ad' button."

Skype says that: "With 145 million average monthly connected users for the fourth quarter of 2010 and 29 million concurrent users at peak times, Skype's reach and engaged user base makes it an attractive platform for brands to market their products."

The move represents the first time that advertising has appeared in Skype. Skype's chief marketing officer, Doug Bewsher, said: "The user experience on Skype is always job number one. So, we've spent a lot of time working through the best way to show advertising in the Skype environment. We believe our daily sponsorship ad from one brand per day is valuable for premier advertisers, but doesn't detract from the experience for our users."

In a posting on Skype's blog, Bewsher said: "We may experiment with ads in other areas as well. The ads won't interrupt your Skype experience. You won't suddenly see annoying pop-up ads or flashy banner ads in middle of conversations."

He added: "We may use non-personally identifiable demographic data (eg location, gender and age) to target ads, which helps ensure that you see relevant ads'¦You can opt out of allowing Skype to share this non-personally identifiable demographic data with advertisers from the 'Privacy' tab in 'Tools - Options'."

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