Find carrier

Greeting i also want to know that from which carrier my iphone is?

i bought this phone second hand in mobile market and don’t don’t from which carrier my mobile is and i want to know this because this phone is carrier locked and i want to unlock it please help me to find my carrier.

And if i don’t insert any sim on it then in settings section mobile data option gone invisible and if i insert any sim in my iphone a pop up comes invalid sim