Moments before dawn, Noor ul Islam ascends the steps of South Asia's largest mosque, enters its cavernous hall and says a private prayer before a faintly buzzing microphone. Then the 32-year-old gulps down a deep breath and makes the morning's call to worship -- a forceful yet lilting chant amplified across Islamabad, marking the start of daylight fasting during Ramadan. All across the Muslim world men like Islam, known as muezzins, broadcast the call to prayer, known as the adhan, five times a day. IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES