The ETravelSim Serbia eSIM runs on A1 Serbia (originally branded as VIP Mobile before the 2018 rebrand following its acquisition by Telekom Austria's A1 Group). A1 is one of Serbia's three major mobile networks alongside Telekom Srbija (mts, the largest with strongest rural coverage) and Yettel (formerly Telenor, rebranded 2022). For city travel and main tourist destinations, A1 covers the routes most travelers actually take with growing 5G in Belgrade, Novi Sad, and Niš.