Dual SIM phones come with a variety of benefits, making them a must-have for many people. However, not everyone understands what dual SIM means or how dual SIM phones work. We’re here to explain everything you need to know about dual SIM phones, their benefits, and how eSIMs fit into this picture. What Is a Dual SIM Phone? Dual SIM phones support the insertion and use of two SIM cards on a single device.