What is the CTU (Counter Terrorists Unit [from TV series 24]) called in real life?

I want to become like one of the agents like Chloe, Edgar, Tony, or Michelle from the TV Show 24. I want to work in the office on computers but i have no clue wat the CTU is in real life and like wat the positions are called and everything! can someone PLEASE explain as detailed as possible. I want to know every single information!!!! Thank you!