The interviewer will tell about himself and about company. Later most of questions will be from technical. About your past role, the tools are you working, about microsoft office, little bit networking, how to get ip address. Etc. be prepared for 1 hour. If you are explaining good the interview will go for 1 hour. Any if you are coming from service desk and technical support it will be very easy to crack the interview. Or else it might be very difficult for you. As it's global service desk role, 1st priority will be communication skills. If you are so good in communication and little bit in technical you will crack it.