You will be treated like absolutely dirt by people are aren't as qualified as you to do their jobs. Everyone in the call centre is there for the same reason you are; the economy is on a downturn and a call centre job was the quickest you could get. You will be monitored by OPs managers and team leaders who will literally tell you off if you take too long going to the toilet.
I have received a threat because I was closing an issue on an account I dealt with the previous day and they saw this as not being "available for calls".
This is the modern day workhouse. You clock in at the exact time or you'll be punished. You work non-stop throughout the day or you'll be punished. Say goodbye to evenings and weekends because you can be sure your hours will not allow you those, you'll be in customer service.
I would 100% recommend you avoid employment in Firstsource. You deserve better than minimum wage for a job that will mentally exhaust you and management that will treat you terribly.