ring offvi phrasalphrasal verb, intransitive: Verb with adverb(s) or preposition(s), having special meaning and not taking direct object--for example, "make up" [=reconcile]: "After they fought, they made up."
(telephone: hang up)
挂断电话 guà duàn diàn huà
If you receive an unwelcome phone call, it's best to simply ring off.