Troubled satellite phone company Iridium is being acquired by an affiliate of private equity firm Greenhill for $591 million.

GHL Acquisition said the deal includes $100 million in cash. In addition, Iridium shareholders will get $360 million in GHL shares. The total value of the deal also includes $131 million of debt Iridium held as of June 30th. Iridium said the transaction will allow it to be debt-free and in a good position to replace its fleet of 66 satellites. When the deal is done, the outfit will go public.

Iridium launched its "anywhere" mobile phone service a decade ago, but signed up just a fraction of the subscribers and it tanked with debts of $4.4 billion. The company had just 55,000 subscribers by the time it halted commercial service in 2000. In 1999, a company called Iridium Satellite bought Iridium's satellites and other assets for $25 million.

It relaunched as a mobile phone service in 2001 and has more than 305,000 subscribers and "complete coverage of the entire Earth, including oceans, airways and polar regions."