영어 문장 구조와 해석 부탁드려요

동사가 여러 개 보여서 문장 구조가 헷갈립니다.
that이 생략된 곳이 있는지, 주절의 동사가 무엇인지 알려주세요.

“The Finnish mobile-phone manufacturer that had once been able to comfortably claim that its distinctive ringtone was the most listened-to melody in the history of music is watching its dominance go up in smoke.”