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You can change models of used smartphones yourself! Detailed steps explained
When changing smartphone models, you might strongly associate the process with visiting a carrier shop or electronics store.
However, more and more people are now buying smartphones through online stores or used phone shops and setting them up themselves.Especially with used smartphones, you can often get them much cheaper than the latest models, making it a cost-effective way to upgrade.
This article provides a detailed explanation of the steps and precautions to take when changing to a used smartphone yourself. If you understand the correct procedures, you can switch smoothly without relying on a store.
"Is it okay to use a used smartphone?"
"Where is the best place to buy one?"
We will also answer these questions, so please read until the end.
You can change your used smartphone model yourself!
While changing a used smartphone model might seem difficult, in practice, it's not significantly different from the process at a carrier shop.
It simply involves basic steps such as replacing the SIM card, initial setup, and data migration.
Additionally, if you use the dedicated apps or official support pages provided by carriers or MVNOs, you can easily find clear instructions for setup and data migration.
Steps to change your used smartphone model yourself
Now, let's specifically explain how to change your used smartphone model.
① Back up your old smartphone data
Before starting the model change, first back up the data on your old smartphone.
By securely saving contacts, photos, app data, etc., you can smoothly transfer them to your new device.
For Android, you can easily back up using your Google account; for iPhone, you can use iCloud or other cloud services.
While you can also extract data by connecting to a PC with a USB cable, cloud backup is simpler.
② Replace the SIM card
Once the backup is complete, remove the SIM card from your current smartphone and insert it into the used smartphone.
At this time, please ensure that the SIM card size (nano-SIM, micro-SIM, standard SIM) matches.
If the size does not match, you will need to exchange or resize it at a carrier shop or an MVNO.
When inserting the SIM card, it is safer to do so after turning off the device.
③ Perform initial setup
Boot up the used smartphone with the SIM card inserted and perform basic settings such as language settings and logging into your Google account (Android) or Apple ID (iPhone).
It's a good idea to use Wi-Fi during initial setup, as it makes updates and app installations smoother.
It's also convenient to set up biometric authentication, such as fingerprint or facial recognition, at this time.
④ Migrate backup data
If you backed up your data with Google Account or iCloud, simply logging in will automatically restore your emails, contacts, photos, and more.
If individual app data transfer is required, check the app's transfer procedures (ID, password, SNS linkage, etc.).
For apps like LINE and games that require an issue of a transfer code, operations on the old device are necessary, so it's important to understand the steps beforehand.
⑤ Perform APN settings if using a low-cost SIM
If you are using a low-cost SIM, you need to set up an APN (Access Point Name) to use data communication.
You can enable communication by simply entering APN information (such as username and password) from the settings screen and saving it.
Since the settings information varies depending on the provider, please refer to the official website or manual and enter the correct information.
⑥ Perform an operation check after completing settings
Finally, check all functions such as voice calls, data communication, camera, and Wi-Fi connection to ensure there are no problems.
If it can be used without problems, the model change to a used smartphone is complete.
If you encounter problems such as inability to communicate or apps not launching, you need to recheck your SIM or APN settings, or suspect a device malfunction.
Precautions when changing to a used smartphone yourself
While used smartphones are available at affordable prices, they often come with concerns about quality and warranty. Here, we've summarized key points to consider when purchasing a used smartphone and changing models yourself.
Purchase from a reliable shop
If you only look at the price and use person-to-person transactions or dubious websites, there's a risk of issues with device quality or even getting scammed with fakes.
It's safer to buy from a specialist used smartphone store or a major e-commerce site that thoroughly checks operations and provides evaluations.
It's also a good idea to check if there's a warranty or return policy.
There are 3 types of SIM sizes
There are three types of SIM cards: standard SIM, micro SIM, and nano SIM. Since the supported size varies depending on the used smartphone, please check in advance if the size of your SIM card is a perfect match.
If the size doesn't match, you'll need to go to a carrier store to change your SIM card.
Confirm that the SIM lock is unlocked
If the used smartphone is SIM-locked and cannot be used with other carriers, you won't be able to use another company's SIM card even if you insert it.
Although SIM unlock was mandated from 2021, there are still cases where devices released a little earlier remain locked.
Before purchasing, confirm that it is "SIM-free" or "SIM-unlocked for XX carrier".
Beware of "red ROM"
"Red ROM" refers to devices that have had network access suspended by the carrier due to unpaid device fees, or devices where call reception/notification registration is no longer available.
No matter how cheaply you can buy it, a device in "red ROM" status cannot communicate and is practically unusable, so be careful.
Reputable sellers often provide a "red ROM" warranty, so it's important to check for warranty coverage before purchasing to avoid risks.
Is the operation check complete?
Used devices may have degraded performance in areas like battery, camera, and buttons. Reliable shops offer smartphones that have been checked for operation, and information such as which parts have been replaced is disclosed.
Check if there are any erroneous charges.
If your current smartphone or line contract still has time remaining, changing models at that time might incur cancellation fees.
Depending on the carrier and plan, monthly fees might apply, or payments for device purchase programs might still be outstanding, so check your contract status in advance.
Is the frequency band compatible?
Overseas models and some low-cost smartphones may not support the frequency bands used by Japanese carriers.
In such cases, it might be difficult to pick up signals or you might only be able to use 3G, so please check the supported bands before purchasing.
Can the plan you're contracted for with your old smartphone's carrier be changed?
If you are changing models with a device you prepared, confirm in advance with your carrier whether your current plan can be maintained or if a change is necessary.
If your plan is outdated, you might lose money, or your device discount might disappear and your rate plan could change.
Devices with battery capacity below 80% are a concern.
When buying a used smartphone, the battery degradation status is important.
For iPhones specifically, you can check the maximum capacity in "Settings" → "Battery" → "Battery Health." If it's below 80%, you might experience concerns about battery life and a higher likelihood of sudden shutdowns.
For Android devices, check the battery information in the settings or a dedicated app, or refer to the shop's description.
[How to check iPhone battery status]
- Open "Settings"
- Tap "Battery"
- Select "Battery Health" to display "Maximum Capacity."
It is safe to choose a battery with 80% or more as a guideline.
[How to check Android battery status (varies by model)]
- Open "Settings"
- Look for items like "Device care" or "Battery"
- Check battery usage and estimated capacity (if not available, check with a dedicated app)
How to buy a used smartphone
There are multiple ways to buy a used smartphone, each with its own advantages and disadvantages.
Choose the best method according to your budget and desired conditions.
Buy from a mobile carrier
Some carriers have started handling used smartphones, and you may be able to purchase them at carrier shops or online stores.
Since the devices are inspected and maintained by the carrier, quality consideration is high and support is relatively extensive.
However, the lineup is often limited, and popular models may have low stock.
Buy from a used goods shop
Electronics retailers and specialized used phone shops often sell devices after checking their operation and cleaning them.
Some stores may offer their own warranties, and you have the advantage of being able to physically inspect the condition of the device.
However, stock levels and selling prices vary between stores, so it's a good idea to compare multiple shops.
The official online store for used smartphones and tablets "PRODIG" sells a variety of used smartphones under strict quality control.
Purchase from an e-commerce site
Many shops that handle smartphones are listed on major e-commerce sites such as Rakuten and Amazon.
The appeal lies in the ease of price comparison and the opportunity to take advantage of advantageous sales and point rewards.
While there's the advantage of being able to check store ratings based on buyer reviews, popular models may not see much of a price drop even when used.
Buy from auction sites or flea market apps
When using peer-to-peer transactions, it is often possible to purchase items at a lower price than at shops.
After purchasing a used smartphone, it is recommended to subscribe to smartphone insurance.
Used smartphones pose greater risks of initial defects and malfunctions than new ones.
If a problem occurs and repairs are needed, high repair costs may be incurred.
Therefore, having smartphone insurance in case of a malfunction can prepare you for unexpected damage. Especially for used smartphones where the manufacturer's warranty has expired, having insurance offers the benefit of long-term peace of mind and continued use.
Enjoy your smartphone life by changing used smartphone models yourself
If you understand the process for changing used smartphone models, you can do it smoothly without relying on a shop.
By properly following steps such as backing up data, swapping SIM cards, and initial setup, you can seamlessly migrate to a new device.
If you can get a cheap used smartphone in good condition, you can significantly reduce costs without being tied to the latest models.
Additionally, by using shops that offer insurance and breakdown warranties, you can also be prepared for risks.
