Fring: Ads Are Coming!

Fring has announced that an ad trial is now running on some of the users around the world.
Fring,  a free IM and VOIP client, did not seem to clock-in  much revenues, although the application is very popular.
The ads are banners at the end of the chat window as show in the picture:

The announcement is truly good news to Fring’s Business plan and business model, moreover it is an ultimate test for  the mobile advertising market.
Ads that will be displayed on millions of Fring clients, to users that come from different backgrounds, different languages, different geographies, different age groups Etc.
So how do you create an advertisement campaign on such a personal device to such a varied audience?!
Will the users click on the banners and actually perform or initiate transactions?!
Will they use the integrated VoIP engine to create calls to the advertiser?!

One thing is for sure, the mobile advertising market will have much to learn from this move, and Fring will be the first to know.