It was the practice of the Prophet (peace and blessings be upon him):
"He (peace and blessings be upon him) had two callers to prayer (mu'adhdhins): Bilal and the blind Companion Ibn Umm Maktum."
Hadith Referenceصحیح الجامع الصغیر / حرف الكاف / 4834
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[م] عن ابن عمر. مختصر مسلم ١٩٣، سعد ٨/٣٦٤.