Apple's gradual rollout of carrier billing that started last year with Germany and Russia has reached Japan, where iPhone users can now buy mobile games and charge them to their phone bill, according to sources familiar with the matter.

Starting Tuesday, customers of KDDI, Japan's second-largest mobile phone company, have the option in the Apple App Store to pay by mobile, said the sources, who asked not to be named because the deal hasn't been announced. Japanese consumers who don't have credit or debit cards can participate in the mobile economy.

Carrier billing represents another battlefield between Apple and its chief rival Google, and one where the tech giants are taking very different approaches. Google Play, the app store on Android devices, has been signing up as many global carriers as possible and now has mobile billing availability in 45 markets, including deals with Japan's top three phone companies.

By contrast, Apple has been quite deliberate in its expansion, starting in Germany with Telefonica's O2 in late October, followed by VimpelCom's Beeline unit in Russia five weeks later. On Monday, the rollout hit Switzerland through a deal with Swisscom and Far EasTone in Taiwan.

"Something previously reserved for Android users is now available to millions of Apple customers via Swisscom," the Bern-based carrier said in a press release. "As a result of an extensive collaboration, they can as of now easily pay for digital content in the App Store and on iTunes, Apple Music, iBooks and Apple TV via their mobile phone bills."



Having seen positive results from its initial deals, Apple has several more countries in the near-term pipeline, sources said. With iPhone sales slowing, Apple is touting its growth opportunity in software and services, and the revenue potential from games, music subscriptions, books and cloud storage.