To sub or not to sub during teacher prep time?

Just having some fun with my visuals...I know teacher prep time is an opportunity to get organized for upcoming lessons but I think it is also a time to regroup alone or with other colleagues before the next teaching period. As a special ed teacher, we are often the first to be called at our site during our prep or even during our co-teaching times because they figure our classes can go on without us. It definitely is a guilt trip if we say no but I have found it easier to just not answer my office phone when it starts to ring and I can see it is the front office...so bad to avoid but I figure if it is a true emergency, they would come and find me. I think building a good repore with the staff will be beneficial when there are times we will need to ask for help during their prep time. I would also make sure that it does not happen often that I lean on them during their prep. If there is an ongoing issue with finding subs to cover classes, I would make every effort to figure out how get those classes covered without making it harder on our own teachers.