Ruling on eating suhoor whilst the muezzin is giving the call to prayer

That depends. If the muezzin is giving the adhan for subh (fajr) (he is giving the adhan when dawn has really started), then you must stop eating and drinking, because the Prophet (peace and blessings of Allah be upon him) said: “Do not stop your suhoor when you hear the adhan of Bilaal, for he gives the adhan at night, so eat and drink until Ibn Umm Maktoom gives the adhan.” The basis for this appears in the aayah (interpretation of the meaning): 

“and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night)”

[al-Baqarah 2:187]

If it is known that dawn has come, even without any adhan, such as when one is in the desert etc., when you see the dawn then you should stop eating and drinking even if you do not hear the adhan. 

But if the muezzin gives the adhan too early or there is any doubt concerning whether his adhan has coincided with the dawn or not, then you may eat and drink until you are certain that the dawn has started, whether that is known from a reliable timetable or from a trustworthy adhan which is known to come at the time of dawn. In this case (if the adhan is too early) you may eat whilst the adhan is being given, you may eat or drink what is in your hand, because there is no certainty that the adhan is being given at the right time, rather it is possible.