The SIM Card Is Going Away. That Might Be Annoying.

SIM cards, which have been around since the 1990s, were once the size of credit cards but are now the size of a pinky nail. The gold contacts that occupy one entire side of the especially small nano SIMs allow your phone to talk to the embedded chip, which contains your subscriber ID. An eSIM does the same job, but you can’t remove it from your phone.

In the age of big SIMs, it was common to store contacts on the card as well, which allowed you to move your address book along with your phone number. Now that everyone has the internet on their phones, there’s no reason to do that, as your contact list lives in the cloud. Today, SIM cards serve only to store your account information, and that’s a minuscule amount of data, small enough to be downloaded to an eSIM over even the weakest internet connection.

Traveling is simpler, because you can activate multiple numbers on the same phone. In the past, only those phones with room for two SIM cards, also known as dual-SIM phones, could have multiple phone numbers. Such devices were rare in the US, but eSIMs have now changed things because they’re fully programmable. For instance, current iPhones support eight stored eSIM phone numbers and two active ones, so if you’re traveling, you can simply download a new SIM to your phone. And if you change carriers or just want to change your number, you can do that as many times as you want, though how simple the process is depends on your carrier and your smartphone manufacturer. If you have multiple numbers or travel frequently, an eSIM should make your life a lot easier.

An eSIM can make it harder for attackers to steal your phone number. For many people, their phone numbers have increasingly become a key identifier, as a way to receive two-factor login codes and password-reset links. If your phone is lost or stolen, the ease with which a person can remove its physical SIM card becomes a security issue. Once someone moves that card to another phone, they own your phone number for all intents and purposes. A determined fraudster with control of your phone number can do a lot of damage in a short time. And as for your phone, without a SIM card, tracking it or remotely resetting it becomes difficult. With an eSIM, in contrast, there’s no card to take, so your phone number is subject to fewer risks. And if your phone is locked with a password, no one has any way to transfer that SIM to another device.

If you break your phone, the eSIM is also toast. That means you can’t transfer it to a new device. With traditional SIM cards, you can simply remove the card from your broken phone. You can then plug the card into another phone and be up and running in mere moments, and you never have to sit on hold for assistance while you do it. With an eSIM, you’ll probably have to talk to your carrier about your busted phone.

Carriers have more control over eSIMs. Using a nano SIM works the same way on every phone: Stab the SIM drawer with a pin, pull the card out, and slot it into a different phone. The process for downloading an eSIM is anything but universal. For example, buying a new phone from your carrier should make the eSIM transfer seamless and instant, but if you buy an unlocked phone or you just want to use a different device that you already own, you may have to sit on hold with your provider or deal with other inconveniences.

Downloading a new eSIM is still hit-and-miss. If the built-in download menu fails, you’re at your carrier’s mercy. Apple, on iPhones, is the closest to standardizing the use of eSIMs; when you buy a new phone, if your phone number isn’t automatically transferred during setup, you can go to the cellular settings to download it manually. All major US carriers support this process. Some Android phones, such as the Google Pixel models, include a transfer tool, but it often gives people error messages telling them to contact their carrier. For Verizon and T-Mobile Android phones, you may have to call customer service (on a different phone) and read off a 15-digit phone identifier. Meanwhile, AT&T has a self-service website where you can log in with a PC and scan a QR code with the phone to download your eSIM. If you don’t have another phone or a PC handy, you might not be able to move your eSIM phone number.

eSIM can’t stop phone-number theft at the carrier level. Keeping your phone number on a non-removable eSIM is helpful should you lose your phone, but that isn’t how most people get scammed. The most common way criminals compromise phone numbers is with “SIM jacking.” That’s when the attacker convinces (or pays) a carrier employee to transfer your phone number to a device that they control. Moving to eSIM doesn’t prevent this tactic—your carrier needs to enact and enforce good security practices, and carriers sometimes miss the mark by giving outsourced customer service too much control over your account and not requiring a PIN or password for SIM changes.

Even if you prefer to use a physical SIM card, that may not be an option the next time you buy a phone. Apple doesn’t sell any current-gen iPhones in the US with a SIM slot, and it’s only a matter of time before the same happens with Android. Transfers and activation still run into some inconsistencies on Android, but Google has started rolling out a more functional eSIM-transfer tool that should work even with phones from different manufacturers.

The pain points will decrease as eSIM becomes the default way that everyone manages their phone number. eSIMs offer real benefits, too.

It just might be a little annoying when you first make the switch—and you won’t have a choice.

This article was edited by Arthur Gies and Caitlin McGarry.