The pressure has been on Helio, SK's US joint venture with Earthlink, since it reported a $192m loss last year and projected 360m losses for this year. It hasn’t been helped by the dismal performance of similar MVNOs either: ESPN was closed by its parent, Disney, while Amp’d filed for Chapter 11.

However SK believes Helio will turn a profit by the end of next year and that US subscribers will nearly treble to 200,000 this year. The company said the additional investment will be matched by Earthlink.