Arseniy Gaber focused on backend development in Go, contributing to the livekit/sip repository by addressing a reliability issue in SIP session teardown. He implemented a fix ensuring that the BYE message is sent before closing the media or room connection, which preserves participant header attributes necessary for accurate header mapping across endpoints. This update improved teardown stability and SIP interoperability, reducing inconsistencies during session termination. Arseniy validated the changes through continuous integration and testing to prevent regressions in the teardown flow. His work demonstrates depth in protocol handling and backend engineering, with a focus on robust, maintainable Go code.