Microsoft Software Engineer II interview questions

One of my friends working in Microsoft, forward my resume to one of the managers there. My resume got attention and a recruiter contacted me for a phone interview. The guy at the phone was really cool. After a short introduction, he started to ask me some questions about my research and industry experience. Why I want to join Microsoft. ? * Few questions about OOP and UML ? * He also asked me how to check whether a Binary tree is BST ? write code ? * Given a BST, and a key value, return a pointer in the tree with this key value if available ? if not, retrun a pointer to the node with a key value which is the next smallest (largest) to the given key ? * A Design problem for OOP using abstract classes, interfaces, and inheritance ? I can't remember the details.