I have been to several dispatch interviews and have been rather successful. Make sure that you are prepared for the interview. For example, make sure your appearance is professional. Business attire is always appreciated, as it shows that you are conscientious about the way you present yourself. Also, take some time to familiarize yourself with both the department and the town/city. Compose some questions that you would like to have answered at your interview. The hiring committee likes to see that you have given the position some thought and that you have a genuine interest.
As far as questions go, I have been to interviews where they ask very few and have also been to interviews where they ask many. Some reoccuring questions are about your availabilty i.e., would you be able to work any shift? How would you feel about being asked to cover someone's shift 3 hours before it begins? How would you feel about having to stay late if someone is sick or doesn't show up for their shift? Other questions include: Why do you want this position? Can you multitask? Do you work well under pressure? Are you able to maintain good working relations with supervisors/ co-workers?
Situational questions often end the interview. They do not usually ask many; they are usually very general. For example, what steps would you take after receiving report of a car accident involving a tractor trailer and a car? and, What would you ask the caller in this situation?
If you have anymore questions, feel free to PM me.