Benefits, Pricing & Top Apps Compare eSIM apps for travelers and learn how they work. TooSIM offers quick activation, region-wide plans, clear pricing, and strong support—ideal for country-hopping.

A SIM card, or subscriber identity module, is a small card in your cellphone that lets you place phone calls, send text messages, and more.

These two ways of connecting your phone to a cellular network are very different. We tell you about each and how you can switch from one to another.

But don’t worry, you can still switch cards or change numbers just as easily. Since eSIMs are part of your phone, they’re ...