"How shall I call my collegues and my principal?", you ask. Are we to infer from this that you are a teaching professional? Or are you a student? Who are your collegues? Are you a support staff professional at a college or university? This could make a large difference in the formulation of a response.

I know I will catch some flak for this, but I will have to say that a large portion of the people who are involved in academia seem to be gifted mostly in the field of pretension. They often add to the confusion over terms of address by insisting upon being called, Doctor, to reflect their level of education.

My own personal stance on this is that I refuse to play a part in their pretension and will only address them as Mr. Ms or Mrs.. Those terms of address reflect my respect for the individual as a person. I will not pay homage to someone's degree. The only people I will call Doctor are the ones who practice medicine.