After being released in April 8 for AT&T as part of the carrier's biggest ever marketing push, and expected to sell around two million devices during the second quarter, the Lumia 900 is now available in the UK. The phone brings the latest Windows Phone Tango update, not available on some Windows Phone devices.

Due to a lack of 4G support in the UK, the phone is the HSPA+ version. The device is available from phone retailer Phones4U in white, and Nokia said the black and cyan variants aren't available "immediately." Speaking to The Verge, Nokia said the Lumia 900 would be available more widely across the UK from May 11.

The HSPA+ version of the Lumia 900 also comes with Nokia's Drive and Music apps, and the latest version of Windows Phone: 8773.98. The phone also includes the Tango update, which lowers minimum requirements for Windows Phone devices and places restrictions depending on the specs.

One such restriction is limiting some background tasks if a device has 256MB of RAM, though Microsoft is suggesting developers test apps and the company is also testing available apps. Applications and the About screen of a device will warn users of limitations if Tango is installed. SkyDrive uploads and Bing Local Scout don't work on 256MB devices, however background audio apps continue to run on the restricted phones.

Improvements introduced in Tango include the ability to send pictures and videos via MMS, and the ability to record notes for up to a minute through voice. Other features are a new location icon to indicate when the GPS is in use.

Microsoft hasn't said when other devices will receive Tango, but assured users the update will arrive.

"After the new devices are out, we'll start the process of working with mobile operators to bring an update to current customers. It'll be a few months before we have specifics on that roll out," a Microsoft spokesperson said to The Verge.

A full range of deals can be found on the Lumia 900 Phones4U page, but highlights include a £28.50 per-month plan with 600 minutes, 3000 texts and 1GB of data for an up-front payment of £89 on Orange. Vodafone are slightly more expensive, though offer more minutes and texts: 500 minutes and 3000 texts, with 500MB of data, for £33.50 per month and £29 for the phone.

(reported by Jonathan Charles, edited by Dave Clark)