What is required of one who broke his fast an hour before the Maghrib Adhan, assuming the phone’s timing was correct?

The time for breaking the fast begins with sunset, as the Prophet (peace and blessings of Allah be upon him) said: "When the night approaches from this side, and the day retreats from this side, and the sun sets, then the fasting person has broken his fast." If you broke your fast before sunset, then it is obligatory for you to make up those days, according to the majority of scholars. There is no sin upon you for not intentionally violating the sanctity of the month, because Allah Almighty has forgiven errors, forgetfulness, and what one is forced to do. It is advisable to consult a local scholar and present the matter to him in detail.