It's reported that the US Federal Trade Commission will investigate the way in-application charges are sold and applied by app stores.

It follows recent complaints that 'virtual currency' is too easy to buy, particularly when children are using mobile devices.

Orange customers in the UK will soon be able to pay for content purchased on their Window Phone devices by adding the charge to their mobile phone account. It means they won't need to give their bank information when opening a Microsoft account to buy music, games or apps.

The news comes a week after Research In Motion and Telefonica announced they were working together to introduce integrated carrier billing to BlackBerry App World.

This week's edition of The Fonecast includes its regular look at the latest mobile industry headlines - and it also returns to last week’s GSMA Mobile World Congress.

New shops from Everything Everywhere, mobiles on the tube, the ever-increasing interest in tablet devices and the future of applications are all up for discussion.

Mark Bridge writes:

This week has been dominated by the media frenzy that is Mobile World Congress. James Rosewell and I were at MWC for all four days… but even a podcast every day wasn't enough to include all the news, so expect more reports from us next week.

Research In Motion and Telefonica have announced plans to introduce integrated carrier billing to BlackBerry App World. This will allow Telefonica customers around the world to purchase apps from BlackBerry App World and charge them to their monthly bill.

Customers will also be able to add in-app purchases of digital goods to their monthly bill.