Microsoft first launched XiaoIce ("Little ice") in September as a way to give Chinese citizens a way to chat with a human-like AI while they are logged into services such as Weibo. It's also available to chat with via Xiao Na, the Chinese version of Cortana, for users of the Developer Preview version of Windows Phone 8.1.
Now Neowin is reporting that Weibo users who have a conversation with XiaoIce can win iPhones if they get the chatbot to say certain phrases.
It's a rather odd contest for Microsoft to be running as the company would certainly like to see its Windows Phone devices become more popular in that country. There's no word on how long this contest in China will last, but it seems clear that this is a case of Microsoft prioritizing services over its phones. Such a strategy is not new (see Office on iOS and Android), but it still rubs some people the wrong way.