What is the Ruling of Eating and Drinking During the Adhan of Fajr in Ramadan?

If the fasting person doesn't know that the Adhan is called at (true) dawn; rather, (it's called) like how people call the Adhan; based on calculations, timings and calenders, then there is no harm in him drinking or eating that which is his hand while the Adhan is being given. There is no problem in this, because the Adhan informs one about the dawn i.e., most probably it is the dawn, and the Muadhhin does not call the Adhan by witnessing the dawn. Rather, he gives the Adhan by what he has been made aware of through timings or calenders. It could be such that the dawn has arrived or not (while the Muadhhin has no knowledge of it). And Allah, the Exalted has indeed obligated Imsak (i.e., abstaining from food, drink etc.) only with the distinction (of the dawn from the night). Hence, it's befitting for the believer to take precaution and finish his Suhur before Fajr, before the Adhan so that he doesn't get exposed to doubts. However, if he is able to reduce his intake of food or drink while the Adhan is being given, then what is apparent (to me) is that there is no problem with that if he didn't know that dawn has arrived.