I’m not sure if this classifies as a call center, but here is my tale.
The only work I could find after my STEM degree (I know, depressing) was a temp job at a call center that fielded calls coming in from people who watched a TV commercial about a depression study drug and were interested in participating. We had to go through a series of questions with them. Basically, to be eligible, they couldn’t have any kind of illness, couldn’t have already been diagnosed, and had to be close enough to whatever location could administer the study. So basically, 100% healthy but also depressed. Most people would get kicked out of the study based on some answer to the questionnaire. Some smart ones would figure it out, and call back with different answers. Some others reacted very badly, crying on the phone that this was their last hope, or that they’d just kill themselves. We had to help transfer them to a suicide hotline if it got that far, which I had to do a few times. Being fresh out of college with no experience or training on how to properly handle mental health, it was pretty rough. Not surprisingly, I got depressed. But I eventually found a better job and moved on.