San Francisco-based Boku has formed a partnership with Spotify to facilitate carrier billing in Germany and Italy for the music-streaming company. The agreement includes every major carrier in Germany and one of the leading Italian MNOs.

The two companies have already teamed up in the United Kingdom, and this is the first extension of that partnership. The recent geographical expansion now offers 90 million mobile subscribers across Europe the ability to pay for Spotify Premium subscriptions using only their mobile phone number.

In a press release announcing the expansion, Boku CEO Jon Prideaux spoke of the success Boku has had thus far in Europe:

In the U.K., the default payment method for new Spotify users has changed from credit card to carrier billing … . These new carrier agreements across Europe not only speak to the global appeal of Spotify’s streaming music service, but also the growing appeal of carrier billing for Europeans as a payment method that can now be implemented as a stored payment method in the exact same manner as a credit card.

Boku’s Checkout offers customers the option of paying via carrier billing at the online point-of-sale (see example above). The company works with 300+ mobile operators in 60+ countries and demoed its mobile payment service at FinovateEurope 2011 in London.