Atc Watcher
Regarding your post above, you are technically correct regarding center/sector boundaries.
However,there is no functional difference between a sector boundary and a center boundary within the same country in a modern ATC system even though the physical facilities of the centers may be hundreds of miles apart. When I transit the Cleveland Center / New York Center boundary or the Cleveland / Chicago or the NY/Washington Center boundary yes the controllers are hundreds of miles apart but the radar and communications systems are integrated such that there is no practical difference from being handed off to a controller working another sector within a center boundary. What you imply may be true crossing an international center boundary, like Cleveland/Toronto or Miami/Havana but has no relevance in this discussion as it occurred wholly within the Brazil domestic system.