Virgin Mobile USA has confirmed its plans to buy Helio, the US mobile arm of South Korea's SK Telecom.

A $39 million offer has been made and the deal is expected to close in the third quarter of 2008.

Both companies are "mobile virtual network operators" which means that they resell Sprint wireless service with their own exclusive phones, applications and plans.

Helio has been hitting the headlines because of poor results, and has in fact struggled since its launch in 2005 as a data-centric mobile phone provider.

PC mag explains that it " was supposed to bring exclusive Korean phones and a sense of openness to the mobile landscape but from the very start, had trouble finding its market and focus".

By the middle of 2006, the company was doing better with ploys including its their "buddy beacon" GPS friend-tracking application and Ocean messaging phone, but it still failed to compete with the biggies in the market.

Virgin Mobile will now take over Helio's 170,000 customers, but we don't yet know whether the Helio's brand and unique services will continue.