Dual SIM

Dual SIM means running two lines on one phone — typically your home SIM for calls plus a travel eSIM for data.

Dual SIM is a phone's ability to keep two lines active at once. For travel, the standard setup is: home SIM (physical or eSIM) stays on for calls and SMS — banking codes included — while a travel eSIM handles all mobile data.

Modern iPhones and most Android flagships support dual SIM as one physical SIM + one eSIM, or two eSIMs active simultaneously.

The key settings: set the travel eSIM as the data line, disable data roaming on the home SIM (so it cannot bill you), and leave the home line on for incoming texts.