Is the marriage contract valid according to Islamic law if the marriage was conducted over the phone, and the witnesses heard the offer and acceptance?

What has been done is not permissible Islamically and is not considered a valid marriage. The matter of marriage is grave, and its conditions for validity must be met, among the most important of which are the woman's guardian (wali) and witnesses. This marriage is invalid because it lacks both a guardian and witnesses. It must be annulled. If there is a desire to continue the marital relationship, the contract can be renewed with its required conditions. The child is attributed to the father due to shubha (definition) (resemblance/doubt). Two matters should be noted: First, the guardian does not have the right to prevent a woman from marrying a suitable man without a legitimate Islamic reason. Second, there should be no laxity in matters concerning private parts, and it is crucial to consult scholars before undertaking any action.