The Messenger of Allah ﷺ had only one muezzin, who would call the adhan when he sat upon the pulpit and call the iqamah when he descended. Abu Bakr did likewise, and so did Umar, may Allah be pleased with them both.
حدثنا يحيى بن آدم قال حدثنا ابن إدريس وأبو شهاب عن محمد بن إسحاق عن الزهري
ما كان لرسول الله ﷺ إلا مؤذن واحد يؤذن إذا قعد على المنبر ويقيم إذا نزل وأبو بكر كذلك وعمر كذلك رضي الله تعالى عنهما
Its isnad is sahih. Yahya bin Adam bin Sulayman al-Kufi, Abu Zakariya al-Umawi, their freedman, is trustworthy, firmly reliable, a hafiz, and a man of excellence. Ibn Idris is Imam Shafii, the founder of the school. Abu Shihab is Musa bin Nafi al-Hannat, whom scholars have declared trustworthy, and his hadith appears in the collections of the two Shaykhs and others. The hadith has already appeared at 15656.