Interviewers are usually team leaders. Once in awhile, team managers will be doing the interviewer. Therefore it depends quite mostly the type of interviewer the interviewee is getting. A small written technical test will be given to check on the knowledge of the staff but usually it's not really important for certain team leaders, team manager will see this as priority though. Due to the nature of the job, interviewer tend to ask on customer service skills and maybe a little bit of the technical part.