The future of the mobile industry is pretty clear- it’s all about data. Data revenues have allowed U.S. carriers to keep subscriber ARPU’s relatively stable in the face of 30% declines in voice revenues over the past five years. Look no further than Verizon Wireless’ recent announcement to allow unlimited Skype-to-Skype voice calls over its 3G network to see the future revenue prospects of voice, now a commodity service.

Data revenues, in contrast, are expected to continue their explosive growth, more than doubling by 2013 according to a recent Telecommunications Industry Association report. It’s no coincidence that over the same period smartphone sales are projected to account for more than 40% of all wireless devices sold domestically as the underlying mobile operating systems on these devices are providing the necessary functionality and services that are enabling greater data consumption by mobile subscribers.

At the recently concluded Mobile World Congress, Microsoft made the mobile OS market a lot more interesting with its unveiling of Windows Phone 7 Series, a completely rethought and overhauled, mobile operating system. Having met with glowing first impressions, the largest software company in the world has positioned itself to compete across the entire smartphone OS spectrum- from Research in Motion’s productivity devices to mass market offerings leveraging Google’s Android platform to feature-rich iPhones from Apple. However, without the ability for manufacturers to upgrade their handsets from Microsoft’s current operating system, Windows Mobile 6.x, to Windows Phone 7, Microsoft will need to build adoption for its new platform from scratch. Microsoft, like the entire mobile OS market, has to successfully address three key relationships in the mobile ecosystem, and not just build a great technology platform, in order to win market share.

1. Device manufacturer access. To get an operating system into consumer hands, most mobile software providers need to partner with device manufacturers. Google has attempted to remove any potential barrier for these OEMs to adopt its Android platform by making it free to use, open source and fully customizable. Microsoft on the other hand is continuing with its licensing model for the Windows Phone 7 operating system as well as imposing stringent hardware requirements on its device partners going forward.

It is these requirements, in conjunction with recent events, that make it unlikely that HTC will continue as Microsoft’s primary device partner. First, HTC, which built the Nexus One for Google, just launched its own version of the Android device at the Mobile World Congress. Dubbed the Desire, this handset incorporates HTC’s Sense, a design experience the company is implementing across all of its future devices, regardless of the underlying operating system, which could run afoul of Microsoft’s new partner standards. Secondly, HTC’s soon to launch HD2, the most feature-rich smartphone running the Windows Mobile 6.5 operating system, does not meet Microsoft’s Windows Phone 7 requirements to qualify for an OS upgrade. Considering the close relationship HTC fostered with Google in developing the Nexus One, Microsoft would be prudent to look elsewhere for access to consumers.

Fortunately for Microsoft, LG, the third largest mobile handset manufacturer in the world, and second in the U.S., has announced its intention to be the first OEM to launch a Windows Phone 7 handset this fall. This could result in faster adoption for Microsoft’s new mobile OS especially if other OEMs decide to diversify their operating system portfolio due to Google’s directly competitive Nexus One mobile offering.

Unlike Google and Microsoft, Apple and Research In Motion view their primary businesses as being mobile. Due to this both have vertically integrated the development of handsets and the underlying operating system. This has enabled both companies to enjoy a more direct relationship with consumers and helps ensure a more consistent user experience across their respective handsets. It’s no surprise that combined, Apple and RIM control two-thirds of the U.S. smartphone market.

2. Retail outlet distribution. As Google learned in launching the Nexus One device, working with the network carrier on distribution and marketing is essential for driving sales and adoption. Google’s internet-only, direct-to-consumer approach to selling the Nexus One on T-Mobile’s network resulted in less than 100,000 of these devices being sold in the first month. Contrast that with the launch of Motorola’s Android-based Droid which resulted in over 500,000 units being sold in its initial month. The Droid’s relative success to the Nexus One can be attributed to the coordinated support from Verizon Wireless which (a) has the largest subscriber base and arguably the best wireless network in the U.S. (b) provided distribution for the device through its retail outlets and (c) was backed by a $100 million marketing campaign.

More than any other mobile OS provider, Research In Motion has benefitted from its wireless carrier relationships. With BlackBerry devices available on every major carrier’s network in the U.S., and thus distribution provided through every wireless retail outlet imaginable, RIM has reached over 40% share of the domestic smartphone market.

Apple on the other hand has succeeded in spite of its exclusive relationship with AT&T Mobility in the U.S., primarily because it revolutionized the smartphone experience with the iPhone, but also because it has been able to drive distribution for its device through its own Apple stores.

3. Developer retention. While device manufacturers and wireless carriers are the critical factors in driving smartphone OS adoption, the iPhone exemplifies why developers are the key to retention. In spite of all the grief and anger directed at AT&T by iPhone users, most customers are unwilling to switch wireless carriers due to the personalization functionality provided by the iPhone through its app store. Even with Apple’s frustrating application approval process, developers continue to focus on building for the iPhone platform because it offers the most lucrative revenue opportunity, according to interviews conducted by Gizmodo at the Mobile World Congress, with interest in Android a distant second but growing due to its potential reach now that 60,000 Android-enabled devices are shipping daily.

Microsoft will need to create the same enthusiasm with developers for its new operating system in order to get these individuals to allocate some of their development time and efforts to learn yet another platform. Unfortunately Microsoft lost a chance to jumpstart its efforts by not having a path for them to port their current Windows Mobile apps to Windows Phone 7.

…and the winner is? I agree with Accel Partner’s Richard Wong that fragmentation in the mobile space is here to stay due to technology but also because of varying business models.

Domestically, Apple will determine how the mobile OS market plays out. If it were to end its exclusive arrangement with AT&T and go with a multi-carrier approach, which has proven to be successful from a market share and financial perspective overseas, Apple would control the most lucrative smartphone market in the world due to its strong relationships within the mobile ecosystem versus its competitors.

Worldwide, Gartner Inc.’s prediction that Google’s Android platform will surpass BlackBerry, the iPhone and Windows Mobile in market share in 2012 is fairly safe due to Google’s approach and the economics of its operating system. Google’s interests in the mobile space are squarely focused on search and location-based advertising. As such, giving away its platform makes complete sense. The biggest risk Google faces is getting into its own way by pushing corporate agendas that come at the expense of partner relationships. Developing its own mobile handset, acting like a telecom company by acquiring wireless spectrum or building its own broadband network, and allowing the fragmentation of the Android operating system are all examples of how Google could quickly lose favor with each of the three key relationships in the mobile ecosystem.

Through sheer size alone Microsoft should be able to rebuild most of the market share it has captured with previous iterations of its mobile operating system with Windows Phone 7, but not to the point that will make it a market leader. Microsoft’s continued reliance on a licensing model for its mobile OS and restrictive design parameters will hurt adoption as it competes against a free and open Android platform. While integrating the Xbox experience directly into the Windows Phone 7’s capabilities might be enough to convert some iPhone gaming enthusiasts, Microsoft’s Zune is a distant second to iTunes’ content portfolio, making it difficult to compete with Apple’s overall smartphone offering.

With Microsoft committing $1 billion to develop its new mobile operating system, Research In Motion faces the greatest market share risk. Not only is an acquisition of RIM by Microsoft highly unlikely now, but Windows Phone 7 Series OS is best positioned to compete with BlackBerry’s biggest strength- mobile enterprise email. By bringing Outlook to its mobile operating system, Microsoft can woo traditional BlackBerry users with native email capabilities and additional functionality through its Office productivity suite. Research In Motion has not only taken a preemptive strike against Microsoft but Google as well, which has integrated Google Apps into Android devices, by releasing a free version of its enterprise server for small businesses. With a relatively small application store, RIM will have an even greater difficulty in retaining its mobile OS market share lead in the U.S. over the next few years.

Whatever the outcome the consumer wins, as the competition will continue to breed innovation and enable smartphones to further evolve from productivity devices into personalized mobile experiences- courtesy of the mobile operating system.