Recently everyone is talking about overseas SIM cards, here’s a compilation of several low-cost options

Hello everyone, I’m CAO. This is my second long article. I’ve named my long article series “Twitter friends need, Twitter friends get.” The content comes from web searches, with text editing and image generation mainly completed by Codex. The article is quite long, so please browse the table of contents and pick the sections you need.

Currently, I use a Giffgaff physical SIM card myself, and the experience is good. Other methods have their own pros and cons, so please consider and choose based on your situation. Feel free to discuss if you have questions (#^.^#)

Here’s the main text:

Recently, posts about overseas SIM cards are everywhere on X (Twitter), and the reasons are quite practical:

On one hand, more and more services like Codex, Claude, Google, Telegram, WhatsApp require phone number verification, and even enable two-factor authentication via phone number. Some services are not friendly to +86 numbers, or prefer overseas numbers.

On the other hand, account theft on X is becoming rampant. If you want to increase account security, two-factor authentication is almost a must. And if you want to use phone number 2FA, many people prefer to have an overseas SIM card.

So the question is: How can ordinary people get a low-cost, long-term, stable overseas SIM card?

This article mainly covers four options:

• Xesim: Allows domestic (Chinese) phones to use eSIM

• Giffgaff physical SIM: Low-cost long-term UK number retention

• Giffgaff eSIM: More hassle, but bypasses the physical card

• German O2 eSIM: Higher threshold, but more powerful features

Table of Contents

• Why is using eSIM troublesome on domestic (Chinese) phones?

• Xesim physical eSIM card

• Option 1: Giffgaff UK physical SIM

• Option 2: Giffgaff eSIM advanced玩法

• Option 3: German O2 eSIM

• How to choose the best option for you

• Final reminders

Why is using eSIM troublesome on domestic (Chinese) phones?

eSIM is essentially a virtual SIM card. The normal process is: the operator gives you a QR code or activation code, you scan it with your phone, and the number is downloaded into the phone.

But domestic (Chinese) phones generally do not enable phone eSIM functionality. You can insert two physical SIM cards, but that doesn’t mean you can directly download an overseas operator’s eSIM.

So if you want to use an overseas eSIM on a domestic phone, you usually need a “physical eSIM card” as an intermediate container. Xesim is such a product.

Xesim physical eSIM card

Xesim is not an overseas phone number or a data card. It’s more like an eSIM container.

You insert the Xesim into your phone like a regular physical SIM, then download other operators’ eSIMs into this card. The phone sees a physical SIM, but you actually manage multiple eSIMs.

Official entry points

Xesim official website: https://xesim.net/

Xesim purchase/product page: https://xesim.cc/

Who is it for?

Suitable for domestic Android users. Suitable for those who want to manage multiple overseas numbers on one phone. Suitable for frequent travelers who want to buy local eSIM data packages. Suitable for those who want to use eSIMs like Giffgaff or O2 in a physical SIM slot.

Which version to choose?

X1: For light use, limited download times. X2: Unlimited downloads, better for long-term tinkering with overseas numbers and travel data. X2 Pro: Better for iPhone users, comes with SeedLink to reduce the hassle of needing an Android phone for the first eSIM download.

How to use on Android

• Insert the Xesim into your phone.

• Install the Xesim App.

• Select the corresponding SIM slot in the App.

• Click “Add eSIM.”

• Scan the QR code, or manually enter the activation code starting with LPA:.

• After download, switch to enable it in the list.

Android is generally straightforward, just a few clicks in the App.

How to use on iPhone

• iPhone is more troublesome; many operations require going through the STK menu in Settings - Cellular - SIM Applications.

• For regular Xesim, the first eSIM download may require borrowing an Android phone for assistance. Because iPhone cannot easily use another SIM or Wi-Fi to download configurations to this physical eSIM card.

• With X2 Pro, you can use SeedLink to complete the first download, which is more friendly for iPhone users.

Pros

1. Solves the problem of domestic phones not being able to use eSIM directly. 2. Can store multiple eSIMs, reducing physical SIM slot usage. 3. Easy to use on Android. 4. Suitable for pairing with overseas numbers and travel data packages.

Cons

1. It is not itself an overseas phone number. 2. Different versions have different download limits; check before buying. 3. iPhone experience is more convoluted than Android. 4. If the operator doesn’t provide an activation code, Xesim cannot conjure an eSIM out of thin air.

Option 1: Giffgaff UK physical SIM

Giffgaff is a UK virtual operator that uses the O2 UK network. Its advantages are: real UK phone number, low cost, no monthly fee, suitable for long-term number retention.

If your goal is only to register overseas services, receive verification codes, or perform security verification for X/AI software, the Giffgaff physical SIM is one of the most hassle-free solutions.

How to obtain

Previously, you could apply directly on the official website and have it shipped to mainland China, but now it’s harder. Currently, you can only purchase stock from domestic platforms. When searching, don’t just search for sensitive full names; try keywords like “UK GG envelope”.

These entry points change quickly; availability depends on the situation at the time.

Activation process

Official activation page: https://www.giffgaff.com/activate

Official login page: https://www.giffgaff.com/auth/login

• Open the Giffgaff activation page.

• Click “Activate your SIM”.

• Enter the activation code on the card.

• Register an account, fill in your email and set a password.

• When selecting a plan, do NOT choose a monthly package.

• Scroll to the bottom and select “Pay as you go”.

• Top up to activate; the common minimum top-up is £10.

Retention rules

Giffgaff requires a balance activity every 180 days.

Note: Free reception of verification codes does NOT count as retention activity.

Valid retention actions include:

Send a text message.

Make a call.

Use a small amount of data.

Top up

The most hassle-free method: Every six months, send a text message to your own domestic phone number, prefix with +86 or 0086.

Sending a text while roaming in China costs about £0.3. Two texts a year costs about £0.6. A £10 balance can theoretically last many years.

Essential settings before inserting the SIM

Android phones: Disable features that might automatically send texts, such as Find My Device, cloud service activation, etc.

iPhone: First deactivate iMessage and FaceTime auto-activation.

All phones: Disable data roaming on this card.

Default data card: Set it to your domestic primary SIM.

Operating environment: Connect to Wi-Fi if possible.

These steps are important. Otherwise, the phone might automatically send international texts or use roaming data as soon as you insert the card.

Pros

1. Real UK number. 2. No monthly fee. 3. Low retention cost. 4. Physical SIM is friendly to domestic phones. 5. Good compatibility for registering overseas platforms.

Cons

1. Physical card acquisition is now harder. 2. Must remember to do a retention activity every 180 days. 3. Roaming data in China is expensive; data must be turned off. 4. If e-commerce channels raise prices, the initial cost may increase.

Option 2: Giffgaff eSIM advanced玩法

Giffgaff also supports eSIM, but unlike many operators, it does not directly provide a QR code. It is mainly activated through the Giffgaff App, and it checks whether your device natively supports eSIM.

Official eSIM help page: https://help.giffgaff.com/en/articles/261570-switching-to-an-esim-with-giffgaff

This causes a problem:

US iPhones and overseas Android phones can apply normally.

Domestic (Chinese) phones, even with Xesim inserted, may be judged by the App as “not supporting eSIM”, and the entry point may not appear.

Method 1: Borrow an overseas eSIM device

If you have a phone or tablet native to eSIM support (overseas version), you can go through the Giffgaff eSIM process on that device first.

Then, try to extract the eSIM activation code and import it into Xesim.

This method is relatively stable but requires equipment and some packet capture ability; not suitable for absolute beginners.

Method 2: HookEuicc + Android sandbox

This is a more tinkering approach.

Core idea: Set up a sandbox environment on an Android phone, use HookEuicc to spoof the underlying eSIM capability, making the Giffgaff App think the phone natively supports eSIM.

General flow:

• Prepare an Android phone.

• Install a sandbox tool.

• Install an older version of the Giffgaff App inside the sandbox.

• Install the HookEuicc plugin in the sandbox.

• Install Via browser in the sandbox.

• Open the Giffgaff App and register an account.

• Switch to the eSIM tab.

• Choose no plan, only top up.

• Add a Visa or Mastercard payment.

• After payment, proceed to install eSIM.

• Copy and save the activation code that pops up.

• Prepend LPA: to the activation code.

• Open the Xesim App, manually enter and download.

Notes

This method is not an official normal process. Requires an Android phone. Old versions of the App may stop working at any time. Sandbox and plugins have security risks. For payment, use a virtual card with a controlled limit. Do not install unknown APKs on your primary phone. If you just want peace of mind, buy a physical card first. If you like tinkering, consider this option.

Retention rules

• Giffgaff eSIM, same as physical card, still requires a balance change every 180 days.

• Free reception of verification codes does NOT count.

• Sending a text message is the most convenient.

• Using a small amount of data for retention is cheaper but easier to lose control; not recommended for beginners.

Option 3: German O2 eSIM

German O2 has a higher threshold than Giffgaff, but also more complete features.

It is suitable for those who want a real German phone number, support eSIM, support WiFi Calling, and very low long-term retention cost.

Pros

• A major German operator brand.

• Good number quality.

• Prepaid, no monthly fee.

• Supports eSIM.

• Supports WiFi Calling.

• Can retain number via low-value bank transfer.

• Can regenerate eSIM in the backend, making device switching easier.

Threshold

• Requires a passport.

• Requires a phone with NFC to read the passport chip.

• Must fill in real passport information.

• Requires a real German address.

• Identity verification may require video call or authentication app.

• Best to have a German or European network environment, though not strictly required.

Application process

O2 Prepaid eSIM official page: https://www.o2online.de/mobilfunk/prepaid/esim/

O2 eSIM info page: https://www.o2online.de/service/esim/

Mein O2 login/registration: https://login.o2online.de/signin/XUI/

• Open the O2 prepaid eSIM page.

• Select the 0€ or basic prepaid plan.

• Fill in name, date of birth, email, German address.

• Name and date of birth must match passport exactly.

• Verify email, set password.

• Submit application.

• Choose online identity verification.

• Use the authentication app to scan your passport, read the NFC chip, and take a selfie.

• After verification is approved, log in to the O2 backend.

• Obtain the eSIM QR code or activation entry.

• Native eSIM phones: scan the QR code directly.

• Domestic (Chinese) phones: download via Xesim.

Settings before use

• After downloading O2 eSIM, do not rush to turn on data.

• First do the following:

• Turn off O2 data roaming.

• Set default data card back to your domestic primary SIM.

• Confirm the phone is connected to Wi-Fi.

• Then enable O2.

• O2 roaming data in China is very expensive; never let it accidentally use data.

Retention method

• O2’s retention logic differs from Giffgaff.

• Giffgaff relies on spending for retention; O2 relies more on topping up to extend validity.

• Regular official website top-ups usually have higher amounts, not suitable for those who only want to retain the number. A cheaper method is bank transfer.

General flow:

• Enable O2 WiFi Calling.

• Connect to Wi-Fi.

• Send a text message with the word BANK to the designated service number using the O2 number.

• Receive O2’s reply with IBAN, payee name, and reference.

• Transfer money using a European account that supports SEPA, such as Wise, N26, etc.

• IMPORTANT: Fill in the reference correctly during the transfer.

• Wait for the deposit to arrive; then the validity period will be extended.

The most critical part here is the reference. It identifies which phone number the money should be credited to. If you enter it incorrectly, the money may not go to your number.

If you only want to retain the number, you can transfer a small amount. The specific minimum amount and whether it succeeds depend on the O2 backend, SMS instructions, and actual deposit at the time.

What is WiFi Calling for?

O2 WiFi Calling official info: https://www.o2online.de/service/wlan-telefonie/

WiFi Calling allows you to make calls and send texts using this German card over Wi-Fi.

Its biggest value: While in China, you can use it as if you were in Germany, rather than expensive roaming.

But do not rely on it completely. Unstable Wi-Fi, the phone switching back to cellular, or roaming not being off can incur extra charges.

Additional settings

It is recommended to disable voicemail. Voicemail may cause unnecessary charges.

When managing your O2 account, the web backend is usually more stable than the App. The App may be affected by regional account, language, and login environment.

How to choose

If you only want a low-cost UK number

Choose Giffgaff physical SIM.

It’s the most beginner-friendly. After activation, just do a balance activity every six months for long-term retention.

If you have a domestic (Chinese) phone and want to use eSIM

First buy Xesim.

Xesim solves the device problem, then consider loading Giffgaff eSIM, O2 eSIM, or travel data packages into it.

If you only have an iPhone and don’t want to borrow an Android

Prioritize Xesim X2 Pro.

SeedLink reduces the hassle of the first eSIM download.

If you want a European number with more complete features

Research German O2.

It has eSIM, WiFi Calling, low-cost top-up for retention, but the application threshold is higher than Giffgaff.

If you can’t buy a Giffgaff physical SIM and want to use eSIM anyway

Research the HookEuicc method.

But this is an advanced玩法; not recommended for beginners.

Final reminders

• All fees, entry points, and promotions change; always re-check the official website before operating.

• Overseas cards are not universal code-receiving tools, but they are much more stable than one-time code-receiving platforms.

• Free reception of verification codes usually does not count as a retention activity.

• Set a calendar reminder: remind yourself one to two weeks before the 180-day deadline.

• Before inserting the SIM, turn off data roaming, iMessage, FaceTime, Find My Device, and any other features that may incur charges.

• Use Wi-Fi whenever possible; always keep the default data card as your domestic primary SIM.

• Virtual cards, sandboxes, and plugins carry risks; if you don’t understand them, do not experiment on your primary device or primary bank card.

Simple summary:

Xesim solves “how to use eSIM on a domestic (Chinese) phone.”

Giffgaff solves “how to hold a UK number long-term at low cost.”

O2 solves “how to have a more powerful German eSIM.”

HookEuicc solves “can’t buy a physical SIM but still want to force Giffgaff eSIM.”

If you only need phone number verification and account security for Codex, Claude, X, Telegram, WhatsApp, etc., Giffgaff physical SIM is sufficient.

If you want to manage overseas accounts long-term, travel frequently, or manage multiple numbers on one phone, then Xesim + Giffgaff/O2 will be more complete.