Lg G3 D850 Update

I live out of US.

Want to update my G3 to 6.0

Bought a Cingular card but it says "SIM not provisioned MM #2"

And not able to update (No update available)

When I try at&t membership: "The device you are attempting to activate requires an AT&T 4G LTE compatible SIM card"

Don't knot phone number. Is Cingular an AT&T SIM Card.

Please help what to do...