What Is an eSIM Card? (2023)

You almost certainly have a SIM card: a thumbnail-sized chip that sits in your mobile phone, telling it which carrier and what phone number you use. Now those SIMs are going digital (or "e") and moving your information to a reprogrammable, embedded chip. But not everyone is happy about it. Here's why.

A SIM card is a "subscriber identity module." Required in all GSM, LTE, and 5G devices, it's a chip that holds your customer ID and details of how your phone can connect to its mobile network. SIMs started out around the size of a postage stamp, but have been getting smaller over the years as device makers reclaim more space inside their gadgets for other electronics. An eSIM takes the circuitry of a SIM, solders it directly to a device's board, and makes it remotely reprogrammable through software.

The original drive toward eSIM came in part from the "Internet of Things" industry. Being tiny, and not requiring extra room for a slot, eSIMs can be built into devices like drones, wearables, sensors, and location trackers, where size is of the essence. They can also be soldered into industrial equipment where a SIM card may not be easily accessible. Being reprogrammable from a distance means eSIMs can be managed in bulk. So, say, a company that runs 50,000 vending machines can switch its service plan or provider with the touch of a button from its headquarters.

With smartphones, eSIMs give you much more flexibility in managing your service plans. A fully enabled eSIM device lets you add a second plan, when you're roaming or if you want a separate work line. It lets you switch providers with the touch of a button. And it lets corporate device managers change the service plans on thousands of lines, remotely, at once. It's a powerfully pro-consumer feature, if implemented correctly.

There are some minor consumer downsides, though. With eSIMs, it's harder to switch one plan between devices—you can't just swap the physical card around—and they can make it harder for you to temporarily remove your SIM if you don't want to be tracked by a carrier.

SIM cards come in several sizes. (US Mobile)

Google's Pixels have had eSIMs since 2017, and Apple's iPhones have had them since 2018. So why aren't we seeing eSIMs everywhere?

US carriers haven't shown much enthusiasm for the standard, mostly appearing to be dragged into it by Apple. But even in countries where carriers are more enthused about eSIM, complex problems are slowing down adoption, according to a report commissioned by Mobile World Live and virtual carrier Truphone.

"Adoption is being slowed by a variety of barriers including difficult setup, extended time to market, cost, and poor availability. The latter is the most prevalent, with 53% of device manufacturers pointing to a lack of adequate supply of eSIM technology as one of the main reasons eSIM adoption is not faster or more widespread," the report says. "This points to a problem not with operators but with their suppliers—likely their SIM manufacturers who now must juggle the production of traditional plastic SIMs with the provision of eSIMs."

What Does eSIM Let You Do?

Simply put, eSIM lets you change your wireless carrier, data, or service plan through software. On eSIM devices, in general, you can go to a menu or take a photo of a QR code to change your carrier or service plan on the fly. You don't need to go to a store, wait for the mail, or fiddle with a tiny chip. You can also often use two different lines on the same device, such as a home and work line, or switch between different plans depending on where you are.

Which Phones Support eSIM?

All three major US carriers support eSIM on recent iPhone and Google Pixel models. The folding Moto Razr also supports eSIM. But while the Samsung Galaxy S20, Note 20 series, Z Fold 2, and S21 series have supported eSIM in theory, they haven't supported them in practice in the US, probably because of carrier resistance.

(Several web pages show how to activate an eSIM on Samsung phones, or put them in lists of eSIM-compatible phones; they are referring to non-US models. As of February 23, 2021, I can confirm that my US unlocked model of the Galaxy S20+ does not have eSIM enabled.)

Which Tablets and Laptops Support eSIM?

Apple's iPads have a great eSIM interface, where you just pick your provider and plan from an on-device menu. US Mobile cites some laptops from Acer, Asus, Dell, HP, Lenovo, Samsung, and Microsoft that support eSIM. Apple laptops do not yet support eSIM or cellular data.

Which US Carriers Support eSIM?

All three of the major US carriers support eSIM, but they don't do so with much enthusiasm.

You'll also find eSIM options from roaming-focused carriers Ubigi, Truphone, and Gigsky, from Google's Fi carrier, and from low-cost prepaid carrier US Mobile. The site eSIMDB has a list of virtual carriers that support eSIM, but most are data-only plans; they don't give you a primary phone number.

How Do You Get and Activate an eSIM?

Here are the eSIM support and activation pages for T-Mobile eSIM, AT&T, and Verizon. As you can see, they're pretty bare-bones and buried in the support websites. There are two common ways to program your phone with an eSIM. The simpler one is to pick your provider from an on-device menu, or through a downloadable app, and sign up for a plan that way.

T-Mobile lets you activate an iPhone eSIM through an app. (T-Mobile)

The more complex way (and more common on phones) involves using a carrier's website to generate a QR code, or having the carrier mail you a piece of paper with a QR code on it. You then scan that QR code with a feature in the settings menu of your phone. This is less convenient, but some carriers prefer it because it requires fewer changes to their own systems. A QR-code-based system also works on more phones than an app, which may work only on one OS or phone model.

US Mobile sends you a QR code to scan.

Is There a Downside to eSIM?

Yes, there's one big one. If you're used to swapping your single SIM card between a bunch of different devices—using several phones with one subscription—that becomes much more difficult with eSIM. Rather than just popping a card in, you'll have to go through the activation process each time you swap. Philosophically, your carrier won't have a problem with this, but logistically, it may really scramble the carrier's activation systems and screw things up.

Does eSIM Have Anything to Do With 5G?

Not really; they're just two standards that came about around the same time. But there is one important link. 5G supports many more devices per square mile, which has gotten the industry excited about activating a lot of little, tiny objects with 5G—sensors, drones, and smart meters, for example. These are exactly the kinds of Internet-of-Things devices that tend to use eSIM, for size and convenience. So eSIM will become more common in the 5G era.

Why Do Carriers Dislike eSIM?

Along with the supply and implementation difficulties cited above, US carriers in the past have shown resistance for commercial reasons.

The obvious reason is that eSIM makes it easier to switch carriers, and they don't like that. It eliminates the drag of having to order a new SIM in the mail or go out to a phone store, turning an errand or a multi-day wait into the click of a button. The US carriers dragged their feet at one point while trying to figure out a way to lock phones with eSIMs, but backed off in 2019 under pressure from the US Department of Justice. You can infer from this, though, that they don't love the new standard.

There's also much more subtle (and mostly pre-pandemic) problem here. Carriers rely on store traffic to drive sales of high-profit accessories like extra chargers and earbuds. Getting SIM cards, configuring phones, and getting support gets bodies into stores, where they can then be pressured to buy other things. But eSIM takes bodies out of the stores, and so potentially the profit out of the customers.

Carriers may be changing their minds, though. According to a 2020 study from research firm Omdia, carriers had a "complete shift in mindset, and they now think eSIM is good for business because they want to be digital." Eighty-three percent of the carriers surveyed said they believe eSIM is good for business—although Omdia didn't break that down by country, so it's certainly possible that the holdouts are American.

"Service providers' mindset has shifted. That are now actively working on eSIM rather than obstructing it or waiting to see what happens," according to the study, which cited carrier execs who said the barriers still standing in the way are time to market, consumer education, and quality of customer experience.

For more, check out PCMag's roundup of Best 5G Phones and Best Unlocked Phones.