A couple of weeks back we reported that HandyGames had signed a deal with Greystripe, a specialist agency, to give some of its games away for free, with players instead getting advertisements as well as gameplay instead of paying to play.

Today we found out exactly how it will work.

GreyStripe's new portal, GameJump.com, will give mobile games away for free, instead of charging the £3 to £6 typically levied for downloading decent entertainment on your phone.

Instead of charging you, advertisers offset the costs, and you see their ads. It's a similar system to that found in many PC casual gaming portals. The ads will be full-screen branded 'wraps' around the games, presumably before and after levels or when first loading the game and on exiting the game. (In our early tests we haven't managed to find a game with an advert yet, so we can't tell you exactly how obtrusive the ads are).

You can directly download the games from the GameJump.com website; you can also access GameJump on your phone at http://gjmp.tw. GreyStripe says its games are compatible with most handsets and carriers worldwide.

Beware though of hidden costs. Phone operators are likely to charge for data usage fees to download the games and ads, depending on your tariff, as well as for receiving text messages when download links are sent via SMS.

Greystripe is being very full-on about its new service, saying flatly that 'consumers who pay to play are losing out'. Not everyone agrees, however.

One developer we spoke to about advertising in games, Jim Blackhurst of Eidos, doubted the business model would change the way most of us get our mobile games.

"You don't need to plaster ads around the game and give it away for free to make good revenue," Blackhurst said. "If you do then there's something wrong with the game."

The GameJump.com portal kicks off with 75 games, covering the gamut of new products and golden oldies, and including titles from well-known developers, such as the recently-announced HandyGames offerings. And Greystripe says more games will be added every week.

"We've shaken up the existing model for pay-to-play mobile games and introduced a way for everyone who owns a mobile phone to access and play games for free through our ad-supported network," said Michael Chang, CEO of Greystripe. "By taking a percentage of the advertising revenue, we can offer a wide collection of popular mobile games."

We'll be testing the system to see how well it works from the UK, so watch this space.