بسم الله الرحمن الرحيم
Umme Kulsum is very nice name for girl. It is the name of one of the daughters of the holy Prophet Muhammad (صلى الله عليه وسلم).
And Azan is also correct name for a boy. It means to inform.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.