On Monday, Microsoft said users of phones running Windows Mobile 6.0 and 6.1 can now shop for and download apps from its Marketplace. The Marketplace was initially only accessible by users of Microsoft's most recent software, Windows Mobile 6.5.
It also said that the store now has 800 apps, triple the number available at the launch of the store in October.
But not all of those are available to everyone. Microsoft's website that lets anyone browse through the Marketplace has just 376 applications.
"People may not see all of them on the Marketplace website or smartphone catalogue, either because of regional access or because certain apps have specific device requirements such as GPS, screen sizes, etc.," Todd Brix, senior director of mobile services and platform product management for Microsoft, said in an emailed statement.
The discrepancy between the total number of apps and the number of apps in the online store demonstrates the downside to a business model like Microsoft's, with an OS that can be used on different kinds of phones.
The model allows end-users the luxury of choosing the phone design they prefer, but it comes with limitations in interoperability. However, Google's Android operating system is also running on phones with different form factors. The Android Market has 12,000 apps and so far doesn't seem to have significant issues with application interoperability.
Apple is on the other end of the spectrum, because it makes both the software and the hardware and also runs the app store. That vertical integration is at least part of the reason that there are now 100,000 applications in the iPhone App Store.
Microsoft says there are more than 18,000 commercial applications available for Windows Mobile. Developers of those apps must submit them in order for them to appear in the new Marketplace. Otherwise, they are only available through third-party sites.
"Windows Marketplace for Mobile will not aggregate all available applications, but rather provide customers with a single source for purchasing quality tested applications backed by a money back guarantee," Microsoft said in a statement.