Phone screen :
System design for typical customer care system using chats. Used hashmap and priorityQueue.

Onsite:
Round 1 : In the lines of Design LRU Cache
Round 2 : Similar to FizzBuzz with a Stack
Round 3 : Read webrequest logs and make statistics like which request was hit how many times. Used Trie and improved Trie to store and retrive data. Mostly discussion.
Round 4 : System Design for Mass Emailing campaigns like MailChimp - Screwed up!