What Is eSIM? A Complete Guide to How It Works, Compatible Devices, and Setup [2026]

What Is eSIM

eSIM stands for Embedded SIM. It refers to a small, embedded SIM that is pre-installed inside a device. Unlike conventional removable SIM cards, it does not require physical insertion or removal. It complies with standards established by the GSMA and works by writing carrier information to a tamper-resistant chip called an eUICC.

A physical SIM is supplied as a plastic IC card. By contrast, an eSIM is a component soldered onto the circuit board. Measuring approximately 6mm x 5mm, it is extremely compact and contributes to saving space inside devices. In official specifications from Apple and Google, eSIM is defined as a “rewritable SIM.”

Its most distinctive feature is the ability to rewrite carrier contract information remotely. Users can activate a line with only online procedures, without visiting a store. Documents from the Ministry of Internal Affairs and Communications also position eSIM as a technology that helps promote competition in the mobile phone market and improve user convenience.

How eSIM Works and Technical Background

eSIM operates through a mechanism called Remote SIM Provisioning. At its core is a server called SM-DP+. Carriers store contract information as data called a profile on the SM-DP+. The device connects to this server via a QR code or activation code and securely downloads the profile.

A profile contains the IMSI, authentication keys, and carrier-specific settings. The eUICC can store multiple profiles. However, how many can be active at the same time depends on the device specifications. Many smartphones can stand by with one or two profiles simultaneously.

In the GSMA specifications, SGP.22 is adopted for consumer devices. This differs in management method from SGP.32 for IoT devices. For consumer use, the user switches profiles through operations on the device. For IoT use, the carrier manages them remotely in bulk. The difference between the two is easily confused in operational settings and requires caution.

Communication security is ensured by a certificate chain from a certificate authority defined by the GSMA. Communication between the device and the SM-DP+ is encrypted with TLS. Writing a fraudulent profile is structurally difficult.

Comparison with Physical SIM

The differences between physical SIM and eSIM are pronounced in terms of operation. The main points of comparison are as follows:

• Form factor: Physical SIM is a card type such as nanoSIM; eSIM is board-mounted
• Replacement: Physical SIM is swapped by opening the tray with a pin; eSIM is switched from the settings screen
• Multiple lines: Physical SIM is limited by the number of slots; eSIM can store up to 8 or more profiles
• Loss/damage: Physical SIM carries risk of loss or contact failure; eSIM has minimal physical risk
• Reissuance: Physical SIM requires waiting for delivery; eSIM can be reissued instantly
• Compatible devices: Physical SIM can be used in all devices; eSIM is limited to compatible models

Behavior in dual SIM operation also differs. Dual standby with two lines is possible with a combination of physical SIM + eSIM or eSIM + eSIM. In US models of iPhone 14 and later, the physical SIM slot itself has been eliminated, making them eSIM-only. This is driven by the need to make devices thinner and improve water resistance.

Benefits and Drawbacks of eSIM

The first benefit is speed of activation. Service can be started in as little as a few minutes after applying online. It is not affected by store inventory or delivery lead times. Even when traveling abroad, you can purchase a local eSIM in advance and get connected immediately upon arrival.

Second, managing multiple lines becomes easier. You can handle separate uses — such as work and personal, or domestic and overseas — on a single device. Switching profiles is completed in tens of seconds from the settings screen. There is also no concern about damaging the tray when physically swapping SIMs.

There are drawbacks as well. Procedures when changing devices can become complicated. Because an eSIM is tied to the device, you must delete the profile on the old device and reissue it on the new device. Depending on the carrier, a reissuance fee of several hundred to several thousand yen may apply.

Constraints regarding compatible devices and carriers also remain. As of 2026, the four major MNOs support eSIM, but some MVNOs have plans that do not offer it. On the device side, some budget smartphones and tablets do not support eSIM. Checking compatibility in advance is essential.

List of Compatible Devices [Latest for 2026]

The support status of major manufacturers is as follows. Depending on the OS version, eSIM functionality may be disabled, so updating to the latest version is recommended.

• Apple: All models from iPhone XS onward, iPad Pro 11-inch and later, Apple Watch Series 3 and later. iPhone 13 and later support dual eSIM. Details are provided in Apple Support (https://support.apple.com/ja-jp/111795)
• Google: All models from Pixel 4 onward. Pixel 7 and later support simultaneous standby with multiple eSIM profiles
• Samsung: Galaxy S20 and later, Galaxy Z Flip/Fold series, and some mid-range models from Galaxy A54 onward
• Sony: Xperia 1 IV and later, Xperia 5 IV and later, Xperia 10 V and later
• SHARP, OPPO, Xiaomi: Selected models such as AQUOS sense7 and later, OPPO Reno9 A and later, Xiaomi 13T and later

Carrier support is also expanding. NTT DOCOMO, KDDI, SoftBank, and Rakuten Mobile all offer eSIM. It is also available on online-only plans such as IIJmio, ahamo, povo, and LINEMO. For overseas travel, services such as Airalo, Ubigi, and trifa sell eSIMs with Japanese language support.

The most reliable way to check if a device supports eSIM is via the settings screen. On iPhone, you can tell by whether “Add eSIM” appears under “Settings > Cellular.” On Android, a similar item appears under “Settings > Network & internet > SIM.”

Setup and Activation Procedures

The setup procedure has much in common between iPhone and Android. You need to ensure a Wi-Fi connection in advance, as data communication is used to download the profile.

Setup on iPhone

1. Obtain a QR code or activation code from your carrier
2. Select “Settings > Cellular > Add eSIM”
3. Choose “Use QR Code” and scan the QR code with the camera
4. When “Complete Cellular Setup” appears, follow the instructions to activate the line
5. Perform a test call and verify data connectivity

There is also a method to activate via the carrier’s app. With Rakuten Mobile and povo, the app automatically handles communication with the SM-DP+. No QR code scanning is required, and the entire process from application to activation is completed within the app.

Setup on Android

1. Open “Settings > Network & internet > SIM > Add eSIM”
2. Scan the QR code or manually enter the code
3. After the download is complete, set the line name and default line
4. If the APN is not configured automatically, enter it manually

APN settings may be required for MVNOs. Accurately enter the APN name, username, and password specified by the carrier. If entered incorrectly, data communication will not be established.

Pricing Plans and How to Choose

In most cases, eSIM-compatible plans cost the same as physical SIM plans. NTT DOCOMO’s official website (https://www.docomo.ne.jp/area/e_sim/) also clearly states that there is no difference in monthly charges between eSIM and physical SIM. The choice should be based not on the form factor of the SIM, but on communication quality and the support system.

Guidelines for choosing by use case are as follows:

• Everyday use: Choose an eSIM from one of the four major MNOs or a major MVNO. Prioritize communication stability and availability of support
• Secondary line: A small-data eSIM from povo or IIJmio is suitable. It can be maintained from 0 yen basic fee or a few hundred yen per month
• Overseas travel: Destination-specific eSIMs such as Airalo or Holafly are effective. You can use local MNO networks more cheaply than roaming
• Temporary use: Prepaid eSIMs that can be purchased on a daily basis offer greater flexibility

For corporate use, operations that distribute eSIMs in bulk via MDM are also increasing. By combining with Apple Business Manager or Google Zero Touch Enrollment, the workload for device kitting can be reduced.

Precautions and Troubleshooting

Common issues that occur during operation are summarized below.

When changing devices, it is important not to forget to delete the profile on the old device. If you initialize the device without deleting it, the line will remain tied to the old device and you will need to go through a reissuance procedure. On iPhone, you can delete the profile via “Settings > Cellular > Remove eSIM”; on Android, via “Erase SIM.”

Recovery when a device malfunctions also takes more effort than with a physical SIM. With eSIM, you may not be able to obtain a reissuance code if the device does not turn on. It is advisable to check the reissuance procedure on the carrier’s My Page in advance. Some carriers require resubmission of identification documents to reissue an eSIM.

There are also many misconceptions about SIM locks. Devices released after October 2021 are generally not SIM-locked. Under the Ministry of Internal Affairs and Communications’ guidelines, no SIM unlock procedure is required. However, with second-hand devices, the lock may remain in exceptional cases, so checking via IMEI is recommended.

If you cannot connect, troubleshoot in the order of toggling airplane mode on and off, rechecking the APN, and re-downloading the profile. If the issue does not improve, check the carrier’s outage information. In many cases, it is not a problem specific to eSIM but an issue on the network side.

Editorial Opinion

We assess that the appropriate criteria for comparison are supported frequency bands and flexibility in profile management. Choosing based solely on low price may lead to dissatisfaction with communication quality in rural areas or indoors. Since eSIM can hold multiple profiles, it is rational to divide roles — prioritizing quality for the primary line and price for the secondary line.

We see the pitfall in practice as dependence on Wi-Fi when changing devices and during initial setup. While official procedures state that the process can be completed online, some carriers take time to reissue QR codes in practice. MVNOs without physical stores offer only chat support, and there have been cases where it took time to resolve activation troubles. It would be safer to avoid purchasing an eSIM just before traveling and to perform verification in advance.

We anticipate that the gradual reduction of physical SIM slots will continue going forward. Apple’s US models are leading the way, and eSIM-only devices may increase in Japan as well. With the spread of the GSMA’s new SGP.32 standard, adoption of eSIM in IoT devices and PCs is also expected to expand. Within one to three years, eSIM is likely to become the standard, with physical SIMs limited to specific uses.

References

• GSMA eSIM Specification SGP.22: https://www.gsma.com/solutions-and-impact/technologies/esim/
• Apple - About eSIM on iPhone: https://support.apple.com/ja-jp/111795
• NTT DOCOMO - About eSIM: https://www.docomo.ne.jp/area/e_sim/
• Ministry of Internal Affairs and Communications - Guidelines for Promoting eSIM: https://www.soumu.go.jp/main_sosiki/joho_tsusin/d_syohi/shohi.htm
• Google Pixel Help - Set up eSIM: https://support.google.com/pixel/answer/9449293?hl=ja