A:Answer Depends, mostly on which country, as certain counties use different types of cellular technology for voice and data. The best way to find out is look at the major service providers for the country you're curious about, and see if they follow the S8's radio bands.
2G bands GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2 (dual-SIM model only)
3G bands HSDPA 850 / 900 / 1700(AWS) / 1900 / 2100
4G bands LTE band 1(2100), 2(1900), 3(1800), 4(1700/2100), 5(850), 7(2600), 8(900), 17(700), 20(800), 28(700)
Speed HSPA 42.2/5.76 Mbps, LTE-A (4CA) Cat16 1024/150 Mbps
GPRS Yes
EDGE Yes