For most everyone who has ever owned a smartphone, a SIM card has been part of the equation.
The now tiny, nano-sized version of the Subscriber Identity Module (SIM) is what’s linked your phone to the telecom carrier of your choice, typically AT&T, T-Mobile or Verizon.
Specifically, it provides a form of digital identity that authenticates or verifies your phone to the network, ensuring that it is permitted to send and receive phone calls, texts and data on a given network because there is a paid account associated with it.
What is an eSIM card?
Not surprisingly, the technology associated with a SIM card has shrunk over time.
That has enabled it to evolve from a credit card-sized device to the fingernail-sized version found in many modern phones down to a tiny chip that can be built into a smartphone’s main circuit board. It is a version referred to as an eSIM, or embedded SIM.
Apple first introduced eSIMs into the iPhone starting with the XS, XS Max and XR in 2018. The most recent Samsung phones, including the Galaxy S20 and forward and all of the Z series foldable phones, as well as most modern Motorola devices, now also include them.
Will having an eSIM card change my service?
For many people, this change won’t make a huge difference, because functionally, physical SIMs and eSIMs do the exact same thing.
In fact, all carrier-connected iPhone 13s and third generation iPhone SE’s bought over the last year from an Apple Store, both retail and online, have been configured with the eSIM inside the phone.
Does having an eSIM make it easier to change carriers?
That ease of use meant some carriers were not very enthusiastic about eSIM when the technology first came on the scene, because they were afraid it would be too easy to switch companies.
AT&T points out, however, they have been an active supporter of eSIMs, including enabling support for them on iPads since 2014 and Apple Watches since 2017.
The notion of having to request a new physical SIM card from a new carrier and asking your existing carrier to unlock your phone (a process that, on some older phones wasn’t even possible) was seen as a deterrent for many people to make the switch. In reality, eSIMs have been widely available for four years, and the fears of mass carrier switching have proven to be unfounded.
The potential was seen as a threat for some time. Still, it will be easier to switch between carriers on eSIM-capable phones if you choose to change.
For those who are used to moving a physical SIM card from an existing phone to a new one when they upgrade, the eSIM-only option on iPhone 14 seemingly presents a different concern. But it’s possible to convert a physical SIM into eSIM format within an existing iPhone in one of several ways.
How do you change phones with an eSIM?
First, through a process Apple calls eSIM Carrier Activation, you can have your carrier apply your existing SIM credentials to a new phone, but you have to contact your carrier to do it. On iPhones with iOS 16 or later, you can go through the process on your existing phone and then use eSIM Quick Transfer to send those eSIM settings to a new iPhone.
AT&T has supported eSIM transfers on iPhones since 2019 on earlier versions of iOS. Some Android phones also support device-to-device eSIM Transfer with some carriers, a process that can make things easier for those want to switch from Android to iOS or vice versa.
Several carriers also have apps that let you convert your physical SIM’s characteristics — which include your phone number and the link to your carrier account — to eSIM format and then transfer that to another phone. This method can work with both iPhones and Android devices.
Here’s why an eSIM is interesting tech
The more interesting part of the eSIM story is that it starts to enable some potentially interesting new usage models. On the iPhone 14 and iPhone 13 series phones, for example, there is support for up to eight different eSIM profiles, although only two can be active at once.
You could, for example, set up two different numbers with the same carrier — one for personal and one for business, a practice that is relatively common in many Asian countries — or set up two completely different accounts with different carriers, with an important caveat I explain below.
It’s this capability that T-Mobile used to enable its clever new Network Pass functionality, which allows you to keep your existing wireless plan but to also engage in a 90-day free trial on T-Mobile at the same time.
What’s an eSIM Network Pass?
If you have eSIM profiles from different carriers, only one can be active for data at a time, but this allows you to essentially see how the data service for T-Mobile compares to your existing carrier in a given location.
All phone calls and texts continue to work just on your primary provider with Network Pass.
Other potentially interesting multi-eSIM profile scenarios could also happen with international travel. Imagine, for example, if a US carrier partnered with other carriers around the world so that the US carriers’ customers automatically received an eSIM profile whenever they landed in a new country and received discounted roaming rates.
Admittedly, with the significantly cheaper $10/day international roaming offers available from AT&T and Verizon and some free roaming from T-Mobile, this isn’t as big a concern as it used to be, but it could translate to some savings for frequent travelers.
Speaking of which, one downside to the lack of a physical SIM slot on the iPhone 14 for people who are used to purchasing local carrier SIMs when they travel is that they will no longer be able to do so.
Many carriers around the world are starting to offer eSIM plans that you can select instead, but the process may take some getting used to.
In addition, not every carrier around the world — or even here in the US — currently supports eSIM, which could limit your options in certain instances or at least for a period of time. Given the enormous impact of the iPhone, however, I expect that to change shortly.
New 5G networks could see a boost
Another potential benefit of eSIM is for businesses that have started to set up private 5G networks for their employees.
All cellular networks require their own SIM in order to connect, so for companies that want to allow their employees to be able to have a smartphone that connects to a traditional carrier and to the company’s private network, eSIMs are the perfect choice.
There is one big potential gotcha for all these multi-eSIM scenarios, including T-Mobile’s Network Pass.
Your phone has to be paid for before you can have an eSIM
Before any eSIM-capable phone on any carrier can “accept” another eSIM profile, it has to be fully unlocked, otherwise the phone won’t allow it.
This means it must be fully paid for — not on an installment plan or under a multi-year service contract with a termination fee. It turns out this was also the case for phones that supported physical SIMs as well, but the additional flexibility of eSIMs means that more consumers may run into this situation.
The bottom line is that the new eSIM opportunities only work with phones that have no remaining financial requirements attached to them, which will definitely limit their potential impact.