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Silence itself doesn't indicate the will of the person (Offeree)
and nothing be understand from the state of silent person. The exceptional cases that those silence means consent is not mere silence, but those are silence plus additional circumstances that indicate the will of offeree and the real value belongs to additional circumstances rather than mere silence, because silence doesn't indicate the will of the silent offeree and silence involves consent and dissenting and without additional circumstances it has no value and validity.
Thus, in the cases the intention of offeree communicated
expressly or impliedly to the offeror, is an acceptance by the existence and announcement that will and this legal effect derives from that will and not mere silence.