Is there a difference between the ruling on a distant and unclear adhan regarding imsak and the ruling on a clear adhan that is followed for prayer?

The decisive factor for commencing prayer and abstaining from food and drink (Imsak) in Ramadan is the entry of the prescribed legal time, not the Adhan (call to prayer), whether it is called early or late. If the muezzin calls the Adhan precisely at the entry of the time, then one must abstain upon hearing his Adhan. However, if he calls the Adhan before the entry of the time, then abstention is not obligatory. The prayer times are known by cosmic signs, and one can rely on trusted calendars. The time for Imsak begins with the true dawn (Al-Fajr Al-Sadiq).