The ETravelSim Serbia eSIM is for Serbia only, so data stops the moment you cross into Bosnia & Herzegovina, Montenegro, Croatia, North Macedonia, Bulgaria, or Hungary. Balkans circuit trips — Belgrade → Sarajevo → Mostar → Kotor → Tirana — are common, as are Belgrade-to-Budapest weekend trips. For multi-country Balkan or European travel, ETravelSim sells a Europe eSIM covering 35+ countries on a single plan including Serbia, Croatia, Hungary, Slovenia, and other Balkan destinations. If anything goes wrong with activation, contact support 24/7 via WhatsApp at +65 9236 1258, the on-site chat, or support@etravelsim.com with your order number.