• by Mark Walsh  @markfwal, August 4, 2010

As one of the early VoIP-providers, Vonage in recent years has seen its prospects diminish, with skads of other companies including Verizon and Comcast offering competing VoIP services -- and the likes of Google, Yahoo and magicJack-creator YMAX launching still other Web-based calling options.

Vonage has also long been one of the top online advertisers. Last year it spent $228 million on advertising and marketing overall but still lost 175,000 subscribers while driving up the gross customer acquisition cost by 10%, according to The Motley Fool.

So what's a once high-flying VoIP provider to do to regain some luster? Friend Facebook, the hottest company around.

Vonage's new mobile application launched today. Allowing Facebook users to make VoIP calls to friends on the social network is a clever step. Until now, just about every other type of communication was possible on Facebook except voice. According to Vonage, iPhone and Android phone users simply download the app from the App Store, Android Market or other sites, enter their Facebook log-in, and instantly start to make free calls by clicking on a friend's name.

The app shows friends who have installed the app and those who are available for IM chats.

In a press release, Vonage CEO Marc Lefar promised the new Facebook app was just the start of bigger things from the company: "In the future we will expand on this service to include a wide range of integrated voice and messaging services that change the way people communicate." Pretty vague, but it's not hard to imagine Vonage expanding the app or creating other VoIP apps for other social networks like LinkedIn or MySpace.

On GigaOm, Kevin C. Tofel said he likes the idea behind the new app. "Most of my Facebook friends are people that I'd actually talk to, so as a platform, Facebook provides a cloud-based directory of my contacts that I don't have to manage," he wrote. "Instead, each of my friends manages their own profile information, which is then pushed down automatically to my handset."

But how much Facebook users, especially younger ones, want to call each other is the question. A Pew Research Center report in April found that texting had surpassed voice calling and all other forms of communication as the primary way teens connect with friends. Besides the shift toward texting and non-voice interaction on cell phones, there's also the question of how many of their 600 "friends" people want to hear from on Facebook.

Status updates from people you might barely know are one thing; phone calls, another. The Vonage Facebook app could find its greatest traction outside the U.S., where 75% of Facebook's 500 million active users reside. With greater use of mobile phones as primary Internet access and calling devices in emerging markets, the app could prove a welcome addition to Facebook users globally. It also dovetails with Vonage's increased focus on the international market in the last year.

Based on 33 ratings so far in the App Store, the Vonage app for Facebook is off to a good start, with an average of 4.5 out of five stars. The sound quality in particular is getting strong reviews. "I just downloaded the app and got my friend in Buenos Aires to download it too. We talked for free and it sounded better than my cell phone!" read one comment.

But the company will have to do more to convince investors the app will help reverse its sagging fortunes -- as Vonage's stock price was trading down about 5% at $2.28 Wednesday morning.