Fring, the Israel-based mobile call and chat application provider, has closed a Series C round of financing on top of the $13 million it has raised since its inception in 2006. The capital comes from its entire list of previous backers: North Bridge Venture Partners, Pitango Venture Capital, Veritas Venture Partners and VenFin Limited all participated in the round.

The actual amount raised was not shared, but we’re told that the third round is pretty much on par with the Series B round the company closed in August 2007 (estimated at $12 million when we reported it, but more in the vicinity of $10 million according to information we received later) and that it’s “most definitely not a downround”.

Fring markets an entirely free, ad-supported mobile application that allows users to engage in Web-based social activities, including VoIP calling, instant messaging and social networking. The startup says it intends to use the extra funding to make the app compatible with more mobile environments (Android, anyone?), support more Web-based community services, introduce a couple of new features and make some usability improvements across the board.

When the economy started crumbling last Fall, fring let go 20% of its workforce, although at the time it stated revenues were actually on the upside but it needed to cut costs to extend its runway through 2009.

The company is up against a slew of well-funded startup rivals, including Nimbuzz, Truphone and eBuddy, but also increasingly against Skype, which is eyeing the mobile handset market more and more.