"I am working for an international bank in Hanoi now," my brother said.

My brother said (that) he was working for an international bank in Hanoi then.

My brother said (that) he was working for an international bank in Hanoi now.

My brother said (that) he was working for an international bank in Hanoi at this time.

My brother said (that) he was working for an international bank in Hanoi.