Who was the first mu’azzin (prayer caller) of Islam?

Explanation
Hazrat Bilal called the  first Azan  of   Fajar  prayer First Azan was  called  out in 1 A.H Bilal ibn Rabah is considered to have been the  first muezzin , chosen by  Hazrat Muhammad himself. The Title of  Bilal ibn Rabah : Sayyid al-Muʾaḏḏin Bilal ibn Rabah  Born:  580 AD, Mecca , Saudi Arabia Bilal ibn Rabah  Died: on March 2, 640 AD,  in Damascus, Syria Bilal ibn Rabah's  Place of burial: Bab el Saghir Cemetery, Damascus, Syria while  Hazrat 'Umar  was the  first person  to suggest the calling of  the Azan.