I don't know where the nearest Mosque to me is, I don't get these calls. I do get bells from a couple of churches in the area, but yeah - not for 15 minutes. Do they really go that long? I can see an argument against that.
I'd get behind a standard that outlined how long a bell/prayer call can go for and how frequent/loud it can be. Something everyone needed to abide by. Everyone. Even Mr. Whippy or anyone who wanted to make a sound above a certain level. Regulate frequency and duration for all and I'm good.
But don't single one religion out. That's messed up.