Direct carrier billing company Fortumo today launched a program for app developers to help them acquire additional users for their apps. Developers adding Fortumo's carrier billing SDK to their Windows Phone apps will receive $5,000 in advertising credit to help drive downloads for their apps in emerging markets, according to a press release. 

"The biggest revenue opportunity for Windows Phone developers comes from countries like India, Turkey, Brazil and Poland where Windows Phone has a strong, growing market share," Martin Koppel, COO of Fortumo, said in a statement. "These are also the markets where mobile payments beat credit cards when it comes to in-app transactions. Combining carrier billing with improved app discovery can significantly increase developer income from Windows Phone."

Fortumo in-app payments enable customers to charge digital goods purchases to their mobile operator bill. 

Developers who integrate the Fortumo in-app purchasing SDK will receive $5,000 in advertising credit through the AdDuplex advertising network, according to the announcement. The program is open for anyone who reaches a minimum revenue threshold with their Windows Phone or Windows 8 app. 

In March 2014, Fortumo launched a $1 million fund for developers to support their efforts on Windows Phone. "We almost exhausted our previous program's fund and learned that user acquisition is one of the key challenges for Windows Phone developers. Together we believe we can tackle this issue and help them earn money in the process," Koppel said.

Fortumo provides carrier billing on Windows Phone to hundreds of game developers around the world, including Game Insight, Creative Mobile, Boyaa, Herocraft and Floor84 Studios.

The Fortumo in-app purchasing SDK supports the sale of both single items and virtual credits. The Windows Phone 8.0 and Windows Phone 8.1 versions of the SDK can be used in C# projects; Windows Phone 8.1 version can also be consumed from C++ projects. Additionally, carrier billing is also available to Windows Phone developers using Unity 3D, according to the press release.