Assuming that the prayer calls are of the same decibel level as the church bells, on what basis would you prohibit them?
Islamic prayer calls (through a PA system of amplified loudspeakers) are screaching out spoken words, words proclaiming "Allah as the only one" "Islam is the light"; etc. De-facto promotion of Islam throughout audible city-wide prayer calls via loudspeakers is not the same as church bells.
Church bells chime the Westminister tone on the hour, it is a clock and nothing more.