Surprisingly, I just recently saw an ad for a chiropractic answering service and immediately thought it was a perfect fit for this type of work. Judging by the description on their website, they handle patient appointments and initial communication. I haven't personally worked with them, so I can't share my experience, but it seems like this is exactly what the thread's author is looking for. If I were you, I'd carefully read reviews and case studies, because their highly specialized focus is a big plus.