It's a very thankless job. You get to deal with angry and frustrated people all day, every day. Their stress becomes your stress. You also have very little agency and authority because what you can and cannot do are strictly enforced by organization policy and closely tracked in a variety of ways. So unless the customer's issue fits neatly into one of several pre-defined categories and has a well-documented solution, you have to either route them to another department, or stall them long enough that they give up.

Call center work is one, maybe two notches above manual labor. You are (often) sitting at a desk in an (often) air-conditioned office, and your pay is only slightly below median. But it is soul-crushing in ways that manual labor isn't, which can quickly turn into depression.