Our Guide To eSIM

From mini to micro to nano, phone SIM cards have been diminishing in size. Now they’re effectively moving inside,as David Crookes explains

What is an eSIM?

As the name suggests, an eSIM is an electronic chip version of a SIM card - those tiny pieces of plastic that you insert into a mobile phone so you can connect to a network and use a number. Rather than take the form of a physical item, however, the eSIM is embedded in a chip inside the handset.

How do they work?

A standard SIM (short for Subscriber Identity Module) stores an International Mobile Subscriber Identity (IMSI) number that identifies every user on a cellular network. It also saves the authentication key that validates the IMSI, and can store contact names and numbers. While eSIMs still identify your user login credentials on a network, they also have the capability for that data to be rewritten over the air.

What are the advantages of an eSIM?

When you have an eSIM in your phone, you can switch between mobile networks with ease. There is no need to obtain a physical SIM card for the new provider because it’s simply a case of opening an account and allowing the carrier to reprogram the eSIM with the necessary data. This should eliminate the hassle of switching and make it a more fluid process. There are no demands for PAC numbers and the move should be instant. Any updates to the eSIM can also be completed remotely by the network.

Can’t | have both a SIM and an eSIM?

Actually, yes, you can - and that’s exactly what is currently happening. Apple’s iPhone XS, iPhone XS Max, iPhone XR and later models all feature Dual SIM capability. This means they contain an eSIM, while also allowing you to insert a physical nano-SIM card. The clear benefit of this dual system is that you can still have your pick of networks because only a handful are currently supporting eSIMs.