The ETravelSim Slovakia eSIM is data-only by default, with no Slovak phone number assigned, no incoming calls, and no SMS unless your selected plan specifically includes the UK-based mobile number with free incoming calls (a feature on some ETravelSim European plans). Confirm with ETravelSim support which configuration applies to the plan you select before relying on calls. For most travelers, WhatsApp, FaceTime, Telegram, and Signal handle voice calls fluidly over the data connection. Keep your home SIM active in your phone for OTPs and emergency calls, with cellular data turned off on that line.