It is not permissible to eat after the second athan that announces the break of dawn. This is why the Prophet Salla Allahu Alaihi wa Sallam said: when Bilal calls the (first) Athan, eat and drink as he gives the Athan to,wake up the sleeping and brings the attention to the one who is praying. But when Ibn Umm Maktoom gives the Athan, refrain from eating and drinking.