Believe us when we say it doesn't get much more dramatic than this...Sendo, the UK handset maker that was one of the earliest hardware partners in Microsoft's Smartphone operating system programme, has unexpectedly terminated its plans to sell a Microsoft-based device. The company will instead develop smartphones based on Nokia's Series 60, an interface that sits on top of the Symbian operating system, Sendo and Nokia said today. "This decision, as you can imagine, was not an easy one to make," said Marijke van Hooren, Sendo's director of communications. "We were very close to shipping the product and had lots of customers expressing positive reactions." She said that details of the decision could not be discussed "for legal reasons" but emphasised: "We had to do this." In a brief statement issued on Thursday, Sendo said only that it "has terminated its Smartphone development programme(s) utilising Microsoft Windows for Smartphone 2002 Software". Microsoft and Nokia were not immediately available for comment. "Earlier this fall we reviewed our smart phone strategy. Seeing that the Series 60 fully embraces both our mission and the new strategy we decided to approach Nokia," said Sendo chief executive Hugh Brogan in a statement. The surprise announcement comes only a few days after Sendo's formal launch of the Z100 handset based on Microsoft Smartphone 2002. At the time, Sendo planned to put the handset on the market later this year or early next year in partnership with network providers around Europe. The handset had been delayed several times while Sendo and Microsoft waited for data-centric networks to become more widespread. The Z100 will now be cancelled, as Sendo no longer has a licence to the Smartphone software, van Hooren said. The decision was influenced by the use of open standards such as MMS (multimedia messaging) and Java in Nokia's and Symbian's software, Brogan said. Sendo included Sun Microsystems' Java technology in its Z100 handset running Smartphone 2002, even though Java competes with Microsoft's own .Net. Van Hooren confirmed that the use of open standards "played a role" in the decision to switch to Symbian, and said the access to source code allowed by Series 60 was important. The Z100 may yet live on in some form. At the device's launch a spokesman said the device was capable of running Symbian's operating system, "if we wanted it to." "The technology we use gives us some advantages in quickly adapting to the Symbian platform," van Hooren said. The company would not comment on when it plans to have a Symbian-based handset on the market. "We are now looking at what we have to do to adapt to the technology and how to redeploy our team," said van Hooren. Symbian welcomed the addition of Sendo to the growing list of its licensees, which include Matsushita, Samsung, Siemens and Nokia itself, praising Sendo's "technical expertise and growing market presence". Sony Ericsson is also planning a Symbian device based on a different interface. Nokia emphasised that Series 60 is licensed as source code, allowing licensees to modify the user interface and make their own additions to the platform. Microsoft takes a stricter approach to controlling its software, insuring, for example, that the screen size and user interface is the same for all its licensed handsets. Sendo's move is a blow for Microsoft, which has had difficulty convincing handset makers to adopt Smartphone, and the restrictions that go along with it. The only other handset maker to have introduced a Smartphone 2002 device is Taiwanese contract manufacturer High Tech Computing (HTC), whose handset will be sold in the UK this year by Orange under the brand SPV (Sound Pictures Video). Samsung has also licensed the software but has not yet released a product. Microsoft owns a minority stake in Sendo. "Whether that will change is a question for Microsoft," van Hooren said. ZDNet UK's Rupert Goodwins contributed to this report.