Hello Azin and welcome to this awesome community! Your story was very interesting. Actually I've never got to know anybody who works or used to work in a call center.
It's great that you're now a freelancer and it's always good to meet other people who are also interested in the English language. I'm also not a native speaker but I love English.
I wish you a lot of fun and success out here. If you have any questions or need help within the platform feel free to ask. I'm always willing to help :)