Assalamu`alaykum,
Bismillah.
Bismillah.
Narrated As-Saib bin Yazid:
In the life-time of the Prophet, Abu Bakr and Umar, the Adhan for the Jumua prayer used to be pronounced when the Imam sat on the pulpit. But during the Caliphate of 'Uthman when the Muslims increased in number, a third Adhan at Az-Zaura' was added. Abu 'Abdullah said, "Az-Zaura' is a place in the market of Medina."
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Narrated As-Saib bin Yazid:
The person who increased the number of Adhans for the Jumua prayers to three was Uthman bin Affan and it was when the number of the (Muslim) people of Medina had increased. In the life-time of the Prophet there was only one Muadh-dhin and the Adhan used to be pronounced only after the Imam had taken his seat (i.e. on the pulpit).
As to how many Adhaans should actually be called out for the Jumu`ah prayer, go do your own research. You might want to go through this.
Anyhow, there's one Adhan and one Iqamah for the Jumu`ah prayer.
Wassalam.
