Is it a condition for the validity of marriage that the pronouncements of offer (ījāb) and acceptance (qabūl) be heard directly from the guardian (walī) and the husband, or is it sufficient for them to be heard through a third party? And does divorce occur in this latter case?

Marriage is not valid unless there is an offer from the guardian or his representative, and an acceptance from the husband or his representative, in the presence of two witnesses. Therefore, since the questioner did not utter the acceptance in the presence of two witnesses, the marriage is not valid. Furthermore, offer and acceptance via phone do not validate the contract. Based on this, the contract is not valid, and his divorce does not affect that woman, because she is a stranger to him.