The "Adhan" is the call to prayer in the Muslim world. There are two primary melodies used for the Adhan, one in Rast, and the other, represented here, in Hijaz. Some of the Muezzins (those who recite the call to prayer) are among the finest vocalists in the Arab world, and offer beautiful variations and ornaments on the melody, as is the case here.
See the following analyses:
Jins Hijaz,
Jins Bayati.