This is an interview. The employer wants to know if you are a skill and behavioral fit.They are looking for red flags and may bring up something negative to get your reaction.Have a copy of your resume in front. Professionally answer the phone and make sure there is nothing distracting in the background including music and TV. Do not put the caller on hold for any reason.You would think these are self evident but, as a recruiter I was put on hold, heard loud music or TV in the background and had someone answer the phone with the most amazing personal information.