Who are the two muadhin of Prophet Muhammad?

The two notable muadhin (callers to prayer) of Prophet Muhammad were Bilal ibn Rabah and Abdullah ibn Umm Maktum. Bilal, an Ethiopian slave who converted to Islam, was the first muadhin in Islamic history, known for his beautiful voice. Abdullah ibn Umm Maktum, a blind companion of the Prophet, was also appointed as a muadhin, demonstrating the inclusivity of the early Muslim community.