Fortumo today launched subscription payments using carrier billing for Windows Phone and Windows 8, according to a press release. Developers building apps for Microsoft platforms can now enable carrier billing for users without credit cards in 83 markets.

"Digital content merchants like Spotify and Hulu are struggling to enter emerging markets as the lack of credit cards in these regions results in only a fraction of people becoming paying users," Martin Koppel, COO of Fortumo, said in a statement. "While Fortumo already helps app and game developers grow their revenue through in-app purchasing, subscription billing enables a wider range of developers to increase their payment coverage on Windows Phone and Windows 8." 

Fortumo is currently rolling out subscriptions country by country. Initially, developers can start using recurring billing through mobile payments in 20 countries, among them Brazil, France, United Kingdom, Sweden, Romania, India and others.

Fortumo said in the announcement the biggest countries for carrier billing spending on Windows Phone are Brazil, France, Argentina, Italy and Vietnam. Internal data from Fortumo also shows that Windows Phone users tend to spend more on apps than Android users: the average transaction size on Windows Phone is $2.05, compared with $1.44 for Android apps.

Fortumo's carrier billing solution is used by more than 300 developers on Microsoft platforms, including leading game studios such as Game Insight, Joybits, Creative Mobile, Games2win, Octro, Happy Elements and Boyaa, according to the announcement.

Fortumo's in-app purchasing SDK supports the sale of single items, virtual credits and subscriptions. 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. Fortumo also provides carrier billing for developers using Unity 3D or Cocos2d-x. The SDK supports over 40 currencies and is localized into 32 languages, according to the announcement.