Want proof that Windows Phone 7 Series was a hit at Mobile World Congress this week? Whenever there was a demo on the Microsoft stand this week, the nearby Cboss stand was deserted. When your new smartphone OS trumps scantily-clad Russian models, you know you're on the right track.

Its whizzy user interface grabbed the attention, but entertainment is also going to be a core element for Windows Phone 7 Series – particularly the integration of Xbox Live and Zune. ME sat down with Oded Ran, head of consumer marketing for Windows phone in the UK, to find out more.

“we're not talking about playing Halo 3 on a Windows Phone,” he stressed. “It's about taking your avatar and Gamer ID with you, and if you play Xbox Live casual games, being able to do that too. We're looking to a broad audience, with the availability of high-quality casual games.”

Frustratingly for some developers we spoke to at the show, Microsoft was relatively low on details about how the Xbox Live element will work for them – it's planning to reveal much more information on that at its MIX show next month.

However, it seems that the company will be looking to differentiate its offering from iPhone. “It's not about whether you have 6,000 different arcade puzzle games in a specific category on your app store,” he says. “It's about how good they are – it's not about the number, it's about the quality.”

Ran says Microsoft is also focused on removing as many fragmentation worries for games developers as possible. This could be a sensitive area though. Some developers who ME talked to at Mobile World Congress are concerned that Microsoft may funnel them into its XNA system and toolsets to make games for Windows Phone 7 Series – potentially increasing the costs of porting existing iPhone games across.

Ran didn't say anything on that score during our interview, but he did say this:

“We're looking at how to build things that span across multiple screens – three screens and the cloud, as we call it internally. When we talk to developers who build games for Windows and Xbox, they tell us they would rather not rewrite everything for Windows Phone 7 Series. What we're doing is building a platform for the key game developers, and Xbox has a very strong ecosystem.”

Microsoft will clearly be courting developers on its ability to make them more money. Ran stresses that Microsoft won't be deciding what price games should sell for, but he does say that “these guys don't want to sell games for one dollar”.

The other big entertainment focus for Windows Phone 7 Series is Zune – it's the latest manifestation of the company's determination to make Zune a software platform, rather than just a set of hardware devices. Zune will supply the music and video hub for the new OS, including a content store, media player and social features.

“We've been having lots of questions about when we'll bring the Zune HD to countries other than the US,” says Ran.

“We're making it quite simple: every Windows Mobile 7 Series handset will have Zune functionality on it. In the UK specifically, we're going to make sure we nail down what the UK audience expects from a great music experience. We haven't really seen much innovation when it comes to mobile music experiences, and this is something very different.”

The new Windows Phone OS also bucks the current industry trend for customisable smartphone platforms, where the likes of HTC, Sony Ericsson and Motorola have been layering their own user interfaces on top of, say, Android.

Is it a wise move to buck that trend? “What we want is a bit more consistency,” says Ran.

“We're raising the bar a bit on that. Developers absolutely get it, and want that consistency – they don't want to write once then have to debug everywhere. We're looking to strike balance, but we have no intention of owning the stack, or competing with partners. We're not going to keep the best version for ourselves and give you a version that's a month older...”

A clear reference to Android, that.

Can Windows Phone 7 Series turn Microsoft's smartphone fortunes around? It's certainly a big leap on from previous versions, although there's a complication with the fact that Windows Mobile 6.5 has only just been released. Outside the enterprise market, consumers and handset makers alike will presumably hold on for the debut of the whizzy new OS at the end of this year.

Can it really compete against the twin juggernauts of iPhone and Android, though? “People tend to forget that this remains a highly dynamic industry when it comes to market share,” says Ran.

“People are changing their phones every 12-18 months, so things can change quickly. Look at Siemens' market share five years ago and now, or indeed iPhone and Android. It's a very dynamic world, and users will vote with their choice.”

Finally, ME asks about handset differentiation. One of the themes at Mobile World Congress has been the increasing commoditisation of handset specs when it comes to smartphones – they're increasingly looking the same, with similar features and chipsets.

Microsoft has set out fairly strict hardware specifications for Windows Phone 7 devices, and it's also not letting OEMs tinker with the UI. Are smartphones the new PCs, with little opportunity for differentiation?

“We would absolutely love to see differentiation in this world, and consumers would too,” says Ran. “In a sense, we hope that us assuming a bit more control over minimum requirements and the user experience will channel more creativity [from the OEMs] towards form factors. We may also see handsets that are more targeted at music and video, or gaming.”

An actual Xbox phone? The problem here, of course, is that this would presumably have to be a Microsoft device, leading the company into the exact same issues shown by Google and its Nexus One that Ran says Microsoft is keen to avoid.

2011 will clearly be an interesting year for Microsoft's smartphone ambitions, which will sink or swim based on the strength of support from handset makers and operators.