Virgin Mobile USA is buying Helio, a struggling cell phone carrier that was founded to bring the advanced features of South Korean phones to the U.S. market, the Associated Press reports.

Virgin Mobile said Friday it would pay $39 million in stock for Helio, which has 170,000 subscribers.

At the same time, Virgin Group and SK Telecom, the South Korean carrier that is the majority owner of Helio, will each invest $25 million in Virgin Mobile. That will give SK Telecom a 17 percent stake in Virgin Mobile.

Virgin Mobile indicated that it will keep operating Helio’s advanced data services and its customer-service plans.

Virgin Mobile had 5.1 million customers at the end of March, making it one of the largest U.S. “mobile virtual network operators,” or MVNOs. Rather than owning their own network, MVNOs buy wholesale airtime from other carriers.