Is marriage via telephone, without witnesses, without the presence of a guardian (wali), or without an authorized marriage official (ma'dhun shar'i), considered a valid marriage, or does it fall under the ruling of zina (fornication)? And is there a permissible Islamic solution for this situation?

Whoever is ignorant of the Sharia rulings must ask before undertaking an action. For a valid marriage, there are conditions that we clarified in Fatwa No. 30897, in which we explained that the preponderant opinion is that of the majority regarding the requirement of a guardian, contrary to Abu Hanifa. However, the matter of witnesses remains. If there are no two witnesses to the marriage, it is not valid according to any of the four schools of thought. In addition to this, conducting the contract through modern communication methods is fraught with much ambiguity, and many scholars have prohibited its validity, and a resolution was issued by the Islamic Fiqh Council concerning it. Refer to Fatwa No. 81830 for details. Informing her family afterwards does not validate this marriage, nor does it make it sound. Therefore, the contract must be renewed, fulfilling all conditions. There is no blame upon you for what has passed, and that cohabitation is not consideredzina due to ignorance of the Sharia ruling. If there are children from this marriage, they are attributed to you in lineage due to the شبهة (doubt/semblance of validity).