According to a document filed with the SEC, Virgin Mobile USA now gets paid $4.50 for each subscriber it signs on to the Sprint Nextel network between July 1, 2008 and Dec. 31, 2009, MocoNews reports.

To put the change in context, here's the back story: When Virgin bought Helio, the media-oriented MVNO piggybacking on Sprint's network, Virgin used the event as an excuse to renegotiate more favorable terms with Sprint. The new deal is an increase from $2.50 per subscriber that Sprint paid Virgin Mobile before July 1st, 2008.

"At the end of Sept., Virgin had 5.2 million customers, and Sprint had just above 50 million, but has lost millions this year," the article said, calling the latest deal an example of "just how desperate Sprint is to stop losing customers." Sprint is the only major U.S. carrier to have lost subscribers in 2008; the other three (AT&T Wireless, T-Mobile, and Verizon Wireless) all posted significant gains.