Before You Pass On an Old Phone

Data does not always disappear

Data remanence is the residual information that can remain on storage after deletion. Simply deleting photos is not enough. A factory reset restores the device to its original software state and is the standard step before passing it on.

The order that avoids lockouts

1. Back up photos, messages and files.
2. Sign out of your accounts and remove the device from "find my device" features.
3. Move any authenticator apps to your new phone first.
4. Remove the SIM card and any memory card.
5. Perform a factory reset and check that it has finished.

Your number is part of your accounts

Many services use two-factor authentication by text message, so your phone number works as a key. If you change number when you change phones, update it in every account before the old number stops working. Otherwise the next sign-in code goes nowhere. When codes do not arrive, it is usually the number, the signal or a message filter. A clear step-by-step example, written in Traditional Chinese for one online service, is this guide to troubleshooting text-message verification codes that never arrive (收不到簡訊驗證碼的五步排查法); the same checks apply to banks, email and any other account tied to your number.

Where the phone can go next

• A family member or friend.
• A trade-in or refurbishment programme.
• A charity that accepts working devices.

Revised 2026-10-22