It was a 45 min phone interview. HR and two hiring managers were on the phone. At first HR gave me a brief introduction of the interview procedures and he asked a few basic behavioral questions, like why you chose our company, why not pursuing a phd degree, etc. The behavioral questions lasted for 30 min and for the rest 15 min, hiring managers started to ask me technical questions. It seemed that they required someone who knew the mass transfer and heat transfer very well, but I had to admit that I did not learn the mass transfer before. My "honest" answer led to a silence of the conversation and I felt that they lost their interests immediately. I think I did great in the behavioral questions because the HR kept saying "Excellent" every time I answered a question. But my technical questions part was a failure because I am lack of the skills what they really need. I received a call from HR two weeks later letting me know that I would not be considered for the on-site interview.