Nokia and mobile app monetization exchange Inneractive have joined forces to launch a  new mobile monetization platform called the Nokia Ad Exchange, or NAX for short.

Announced today at the Microsoft Build developer conference, NAX is essentially a white-labeled version of Inneractive’s platform, launched under the company’s private exchange line of services. Other companies that have created their own private exchanges with Inneractive include StackMob, Unity and Corona Labs.

NAX is cross-platform, and supports Windows 8, Android, iOS and Blackberry. The service will allow developers to to buy and sell advertising inventory through mechanisms such as real-time bidding and hybrid mediation. NAX will also have access to Inneractive’s stable of 120 mobile ad networks including InMobi, Adfonic and Amobee.

“With the launch of NAX, Nokia will enable developers to simply and effectively monetize their apps, as part of our continued focus on supporting the developers ROI to build successful businesses” said Richard Kerris, VP & Head of Global Developer Relations, Nokia in a statement.

The move is an interesting one, given that Nokia is primarily known for manufacturing mobile phones, rather than providing the services developers use on its hardware. However, with the company’s market share dipping and Microsoft partnering with other manufacturers to create Windows 8 smartphones, it makes sense for Nokia to diversify its product offerings and keep itself open to other platforms.

Using Inneractive’s technology also means Nokia can use its new ad exchange to help foster the Windows 8 app ecosystem, explains Inneractive’s co-founder and president Offer Yehudai.

“I think Nokia made a very interesting move when they opened the Nokia Ad Exchange to all platforms. I think it’s a very open minded plan,” he says. “Developers can use the Nokia Ad Exchange on any platform, and they can take ad revenue from one platform and use it to promote their apps on different platforms. If you have an Android app you can use that ad revenue in the exchange and use it to promote your Windows Phone application and vice-versa.”

Considering that iOS and Android both now have more than 700,000 available apps compared to the 100,000 currently available on Windows Phone,  it’s easy to see why Nokia would be interested in a solution that could be used to bolster the ecosystem the company is betting its handset business on.

Inneractive is backed by $8.5 million in venture funding from Evergreen Venture Partners and private investrors such as Andy Fruchter and Ehud Hillman. The company closed a $3.5 million round of Series B funding in August.