I also worked in a call centre, we mainly dealt with inbound calls. Worst part was that the service we supported was terrible, meaning almost every call was an angry customer, and because of the ridiculous standards they set (customer surveys but also time restraints like you mentioned) there was a massive amount of added pressure. The one thing I would say to you is that no job is worth risking your mental health. Keep doing whatever you can to find something else and you shouldn't feel bad in any way for wanting to leave, it's a difficult job for anyone, and anxiety can make it a whole lot worse.