Who was the first muezzin in Islam?

The preponderant view is that the first person to call the adhan (call to prayer) was Bilal, may Allah be pleased with him. This is based on what Al-Bukhari narrated from Abdullah ibn Umar, may Allah be pleased with both of them, that when the Muslims arrived in Medina, they gathered and discussed the method of calling to prayer. Some suggested a bell or a horn. Umar then said, "Why don't you send a man to call for prayer?" Thereupon, the Messenger of Allah, peace and blessings be upon him, said, "O Bilal, stand up and call for prayer." As for the hadiths indicating that the adhan was widespread in Mecca before the Hijra, Al-Hafiz Ibn Hajar said about them, "None of them are sound."