Sendo, a British mobile-phone start-up, partnered with Microsoft to build one of the first Windows smartphones, then abruptly dropped Microsoft in late 2002 for the rival Symbian platform. In December 2002, Sendo sued Microsoft, alleging that Microsoft had used the partnership to extract Sendo's proprietary technology and trade secrets and then funneled them to a competitor. Microsoft denied the allegations and filed a countersuit for breach of contract. The companies settled in 2004, with both sides denying liability; Microsoft surrendered its roughly 4 percent stake in Sendo and paid an undisclosed sum. The case added to a pattern of partners accusing Microsoft of appropriating their technology.