Samsung Galaxt Note 8 AT&T Unlocked (International update issue)

I have a Note 8 AT&T unlocked version. I stay in India. I'm not able to update my firmware via OTA or Smart switch. It says "software up to date". I do not have an ATT sim with me. How do i update my software now? Also, is there a way i can remove the "Service Provider software" to make it a completely stock phone and without the ATT software.

will flashing a stock firmware from sammobile help?

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