Callsign blocks:- DU-DZ 4D-4I. ISO 3166 code:- PHL.OC Timezone:- (daylight savings time applies) Amateur Allocations are as follows:- DU1 DU2 DU3 DU4 = Luzon DU5 = Leyte DU6 DU7 = Panay, Negros & Cebu DU8 DU9 = Mindanao