The new phone is on the desk, still in its box. Apple's and Google's transfer tools do most of the work, but some things don't move by themselves, and finding out after you've wiped the old phone can be costly. The classic case is the two-factor authenticator app: if the codes stay on the wiped phone, getting back into several accounts becomes a serious problem.
Here is the sequence I follow and recommend, split into three stages.
Before: preparing the old phone
1. Update and make a full backup
Updating the system and apps on the old phone reduces incompatibilities. Then a full backup: iCloud or a computer for iPhone, Google backup for Android. Check the date of the last successful backup, not just that the feature is turned on.
2. Check your photos
If you use a cloud photo service, check that the upload is complete. If the photos are only on the phone, copy them to a computer too: two copies are better than one, especially during a move.
3. Take stock of authenticator apps
This is the critical point. Apps that generate six-digit codes (Google Authenticator, Microsoft Authenticator and the like) behave in different ways:
- some sync codes to a cloud account, if that option was turned on;
- others let you export accounts to the new phone via a QR code;
- in other cases you have to sign in to each service and register the device again.
Before going ahead, make a list of the protected services and check that you have each one's recovery codes, stored somewhere safe such as a password manager.
4. Chats and apps with their own backups
Some messaging apps have a backup separate from the system's: it has to be turned on and checked from inside the app. Pay particular attention when moving between iPhone and Android, where transferring chats requires specific procedures that vary from app to app.
During: setting up the new phone
Guided transfer
- iPhone to iPhone: bringing the two devices close together starts a direct transfer that copies data, settings and apps;
- Android to Android: setup offers to copy data from the old phone, by cable or wirelessly;
- between different systems: there are official migration apps that transfer contacts, photos, calendars and, in some cases, chats.
A cable transfer is usually faster and more reliable than a wireless one, when both phones support it.
The phone line
With a physical SIM you just move it, perhaps with a size adapter. With an eSIM you need the transfer procedure offered by the system or a new profile requested from the carrier. Either way, it's best done while you have another connection available, such as your home Wi-Fi, so you can receive any verification codes.
Apps that need a fresh sign-in
Banks, payment apps and work apps usually don't transfer the session: they require a new sign-in and often an identity check. That's normal, and it's a security measure. Tackle them calmly, one at a time, with credentials and documents to hand.
After: verify, and only then wipe
Before resetting the old phone, a final check:
| To verify | How |
|---|---|
| contacts | a sample of names, numbers included |
| photos | the most recent shots are there |
| chats | important conversations are present, with attachments |
| authentication | a test sign-in to every protected service |
| banking apps | successful login and notifications working |
| smartwatch and accessories | paired with the new phone |
Only when everything works do you move on to preparing the old device.
Preparing the old phone for resale or recycling
- Remove the main account: on iPhone turn off "Find My" and sign out of your Apple ID; on Android remove the Google account. Otherwise activation lock will stop anyone else from using it.
- Unpair accessories: unpair the smartwatch from the old phone, if it hasn't already moved to the new one.
- Reset to factory settings, choosing to erase the eSIM too if there is one.
- Remove the physical SIM and any memory card.
On modern phones storage is encrypted: a factory reset deletes the encryption key and makes the data unrecoverable in practice. No special multi-pass erasing procedures are needed.
The most common mistakes
- Wiping the old phone the same evening, without checking the authentication codes.
- Forgetting a chat app's internal backup, relying on the system one.
- Selling the phone with the account still linked, leaving it unusable for the buyer.
- Losing data from a health or fitness app not covered by the backup.
In short
- Make a full backup and check its date before doing anything else.
- Authenticator apps are the critical point: export the codes and keep the recovery codes.
- Guided transfer copies most data; banks and work apps need a fresh sign-in.
- Check everything on the new phone before wiping the old one.
- Before selling, remove the main account to lift activation lock.
