It sounds like you have one of the quite rare speech therapists who is trained to address dysfluency. Many of us went to SLP's who had no training in helping our issue and may have made us worse. You sound scared and that's good, because that means this is the right exercise for you. (This exercise was the very first thing I did when I began my journey to gain control over my speech, so I know how scary it can be.). If you truly have no emotions about blocking, then your situation is very very rare because blocking usually IS a response to fear/anxiety. The 5-10 minutes you spend on the phone will not negatively impact your parents' time or anyone from the companies you call. You do not need to call a place that's nearby. I'm sure you can call a restaurant/bar and ask about their specials, whatever. Ask your therapist why they gave you this assignment. I bet they will say it's even better to do the assignment in person (beginning by advertising your stutter).