Why does anyone need to be called to prayer? Don’t they own watches?
It's a standard practice of Muslims to force their religion on others. The loud call to prayer 5 times a day is intended as an oppressive behavior by Muslims directed against the non-Muslim population. It is also intended as a form of subjugation to keep the Muslims "in line". A watch would do the job just fine, but that wouldn't serve the ulterior purposes of the Islamic radicals.