Because completed certification courses are required for some jobs like administration or clerical work. It looks great on ur resume and proves u had previous experience with a related job position. Most companies won't hire if u don't have previous experience or knowledge of so within get related to that job, also they won't hire if he a noob! There is also the fact that upon completion of a course that u might get a few job offers from workforce centers or the training class it's self like when I was doing a forklift class with goodwill

Why would you need any kind of certification to work CS in a call center? And nothing against call centers, I've worked in one but have never heard of any kind of certification.