eSIMとは？メリット・デメリットをわかりやすく解説【2025年最新版】

eSIMとは？メリット・デメリットをわかりやすく解説【2025年最新版】

／Last updated: August 26, 2025

“I want affordable and easy mobile data abroad.” “Changing SIM cards is a hassle.” eSIM solves both problems. This article explains what eSIM is, its pros and cons, and how to use it — with a link to purchase at the end.

What is eSIM? (How it works and how it differs from physical SIM cards)

eSIM is an embedded SIM built directly into your smartphone. No need to insert or replace physical cards — simply scan a QR code or enter an activation code to download your mobile profile.

Physical SIM

Switch carriers or plans by replacing the card.

eSIM

Activate or add profiles online — no physical card needed.

※Available only on supported devices (iPhone/Android). Some tablets, PCs, and smartwatches are also compatible. You can check support in your device settings under “Mobile Data / SIM.”

Benefits of eSIM

No Physical SIM Needed — Start Using Immediately

Activate within just a few minutes after purchase. No shipping or store visit required — perfect for last-minute travelers.

Easy to Purchase and Activate for Overseas Trips

Buy a plan → scan the QR code → turn on data roaming upon arrival to start using instantly.

Affordable Plans

Compared to Wi-Fi rentals, eSIM provides cost-effective data access while abroad.

No Risk of Losing Your SIM

Since the SIM is built into your device, there’s no risk of losing it while traveling.

Drawbacks of eSIM

Limited Device Compatibility

Older or SIM-locked phones may not support eSIM. However, most modern smartphones are compatible. Check the supported device list before purchase.

Cannot Be Shared Across Multiple Devices

eSIMs are generally bound to one device and cannot be used on both a phone and tablet simultaneously.

Network Speed Depends on the Carrier

Connection quality depends on the provider and network. Choose a plan that fits your destination, duration, and data needs.

Setup May Feel Intimidating for First-Timers

First-time users may feel unsure about setup — but it’s easier than you think!

Use Cases of eSIM

  1. 1. Traveling Abroad: Activate Instantly Without Waiting at the Airport

    If you purchase your plan beforehand, you can connect the moment you arrive — no need to wait in line at SIM counters.

  2. 2. Business Trips: Tether Your Laptop

    Use your smartphone’s eSIM plan for tethering to connect your laptop or tablet instantly while on the go.

  3. 3. Short to Medium-Term Stays

    Plans range from a few days to several months — perfect for study abroad or workations, offering a cheaper and simpler option than Wi-Fi rentals.

Summary: Who Should Use eSIM
  • Those who want a reliable data connection even right before departure
  • Those who want to avoid the hassle and risk of swapping SIM cards
  • Those who prefer flexible plans based on trip duration and data usage
  • Those who want to use eSIM smartly for both business and personal travel

How to Use eSIM

STEP.1

Select and Purchase a Plan

  • Check device compatibility (Supported Devices) / Make sure SIM lock is removed
  • Select the best plan by destination, duration, and data (e.g., Asia 7 days / 3GB)
  • After purchase, you’ll receive a QR code or SM-DP+ info & activation code via email

STEP.2

Add eSIM Profile to Your Device

  • iPhone: Settings → Mobile Data → Add eSIM → “Use QR Code” (Manual: Enter SM-DP+ info)
  • Android: Settings → Network & Internet → SIM → Add eSIM → “Use QR Code” (Manual: Enter code in Advanced settings)
  • Once added, confirm that your eSIM name (e.g., Travel eSIM) appears.

STEP.3

Prepare Before Departure → Activate Upon Arrival

  • Before departure: Install only and keep Data Roaming OFF
  • After arrival: Set eSIM as Preferred Mobile Data Line → Turn Data Roaming ON
  • APN is usually set automatically. If not, use the APN info provided in the instruction email.

STEP.4

Connection Test & Troubleshooting

  • Toggle Airplane Mode ON→OFF / Restart the device
  • Switch between 4G/5G or manually select a local carrier
  • If issues persist, see Troubleshooting or contact Support

FAQ

Can I use eSIM and a physical SIM together?

Yes, if your device supports dual SIM. On iPhone, go to [Settings] → [Mobile Data] to select which line to use for data.

Can I use tethering (hotspot)?

Yes, most plans support tethering. Turn on your device’s hotspot feature and set the APN as instructed in your confirmation email if needed.

Can I transfer my eSIM to another device?

Generally, eSIMs are tied to one device. Reissuance or re-download availability depends on the plan and provider. Contact support if you need to switch devices.

What should I do before departure?

Install the eSIM on your device before leaving, but keep Data Roaming OFF. Upon arrival, set it as the preferred data line and turn roaming ON.

What if I can’t connect?

Try toggling Airplane Mode ON→OFF, restarting your device, switching between 4G/5G, or manually selecting a local network. If still not connected, set the APN listed in your instruction email.

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