How to SIM unlock a used smartphone
Have you ever experienced buying a used smartphone only to find it SIM-locked and unusable? If you can unlock the SIM, you'll be able to use it with a different carrier or a low-cost SIM.
This article will explain in detail the mechanism of SIM lock, cases where SIM unlock is not necessary, the unlock procedures for each major carrier, and how to check SIM lock on used smartphones.
Why are phones SIM-locked?
SIM lock refers to a mechanism where a purchased smartphone is configured to only be usable with a specific carrier.
The reason mobile carriers apply SIM locks is that if devices sold on installment plans are brought to other companies and used, there's a risk of losing their own line subscriptions.
Additionally, a significant purpose is to mitigate the risk of unpaid device costs and to ensure the recovery of initial costs.
In Japan, due to the policy of the Ministry of Internal Affairs and Communications, SIM unlocking procedures are becoming more widespread, but it is not completely liberalized.
While it is possible to unlock under certain conditions, it is necessary to confirm requirements such as fees and the period from the date of purchase of the device in advance.
In some cases, SIM unlock is not necessary.
Actually, not all used smartphones require a SIM unlock.
Even with carrier devices, SIM unlock may not be necessary if certain conditions are met.
The table below summarizes the main conditions under which SIM unlock is not required for each major carrier (docomo, au, SoftBank, UQ mobile, Y!mobile).
|
Carrier |
Main conditions for no SIM lock requirement |
|---|---|
|
Docomo |
A certain period has passed since purchase, and the line contract has expired. |
|
au |
Device payment is complete and 101 days have passed since purchase. |
|
SoftBank |
Device purchased in a lump sum or installment payments completed, and 101 days have passed since purchase. |
|
UQ mobile |
Many models do not have SIM locks themselves, and in some cases, no procedure is necessary. |
|
Y!mobile |
Similar to SoftBank, SIM unlock is possible when device payment is complete and 101 days have passed since purchase. |
How to unlock SIMs on major carriers
If a used smartphone is SIM-locked, you can unlock it using the official procedures provided by the carrier.
However, depending on the carrier, it may be difficult for someone other than the original purchaser to complete the procedure, so there may be limitations with used devices.
Here, we will introduce how to unlock the SIM for each carrier.
Docomo
|
Procedure |
Requirements |
Fee |
Notes |
|
Online (My docomo) or docomo shop |
Device payment completed, or more than 101 days since lump-sum purchase |
Online procedure is free, in-store procedure is 3,300 yen (tax included) |
- |
Australia
|
Procedure |
Requirements |
Fee |
Notes |
|
My au (online) or au shop
|
Installment payments completed, or more than 101 days since device purchase |
Online is free, in-store is 3,300 yen (tax included) |
- |
SoftBank
|
Procedure |
Requirements |
Fee |
Notes |
|
My SoftBank (online) or SoftBank shop |
More than 101 days since purchase, device payment completed, etc. |
Online is free, in-store is 3,300 yen (tax included) |
- |
UQ mobile
|
Procedure |
Requirements |
Cost |
Notes |
|
My UQ mobile or store
|
Certain period passed since device purchase, or already paid in full |
- |
Some devices may be SIM-unlocked from the start
|
Y!Mobile
|
Procedure |
Requirements |
Cost |
Notes |
|
Similar to SoftBank, 101 days or more passed, etc.
|
Similar to SoftBank, 101 days or more passed, etc. |
Free online, 3,300 yen (tax included) for in-store procedures |
- |
How to check the SIM lock status of a used smartphone
When purchasing a used smartphone, you need to know if it is SIM-locked or already unlocked.
Since the confirmation method differs depending on the model, we will introduce it separately for iPhone and Android.
iPhone
Open Settings → General → About, and the "SIM Lock" item will be displayed.
If "No SIM restrictions" or "SIM Free" is displayed, it means it's unlocked.
If a carrier name or "SIM Locked" is displayed, you need to unlock it.
Since the display may differ in some older iOS versions, if possible, update to the latest iOS and check.
Android
There are methods to check the device information screen or use an app that can display the SIM card status. In many cases, the "Device Information" or "Network" may not securely show the SIM lock status, so the quickest way is to actually insert a SIM from a different carrier.
If "Network lock is set" appears, it is locked. If "SIM recognized and available" appears, it is unlocked.
Precautions when unlocking SIM
When unlocking a SIM for a used smartphone, the contract status with the seller or previous owner can be complicated, so consider the following points.
-
Check the device status before purchase→Procedures may not be possible with red-flagged devices that have usage restrictions.
-
If information from all previous owners is required
→Depending on the carrier, procedures may not be accepted from anyone other than the purchaser. -
Existence of unlock fees
→There is a difference (e.g., free online vs. 3,300 yen (tax included) in-store), so online procedures are necessary if possible. -
Confirmation if communication is possible after SIM unlock is necessary.
→Due to frequency compatibility issues, it may not be possible to use the network of the desired carrier.
How to Sell a SIM-Unlocked Used Smartphone for a High Price
SIM-unlocked smartphones are easier to sell because they are not tied to a specific carrier. Here are some tips on how to sell such used smartphones for a high price.
Within the warranty period
If the manufacturer's warranty or carrier's warranty is still valid, it provides a sense of security to potential buyers.Selling before the warranty expires may increase the appraisal value.
Gather all peripheral accessories
If all accessories such as the box, included cables, and earphones are present, the appraisal value tends to be higher.
Also, including a screen protector and case as a set will create a more favorable impression.
SD card is wrong
To prevent data leakage, always remove your SD card before selling.
If the SD card is left in, there is a risk of personal information leakage, and it may even be disposed of by the store.
Leave no remaining payment status
If there are remaining installment payments for the device, buyers often shy away from it.
If you can prove that it is completed, it increases peace of mind, including SIM unlocking, and may not affect the appraisal value.
What kind of used smartphones are difficult to purchase?
Even if a smartphone is SIM-unlocked, depending on its condition, it may not be purchased or its appraisal value may significantly decrease.
Below are examples of devices that are particularly difficult to purchase.
Device screen is cracked or yellowed
Devices with screen or display defects may be difficult to purchase due to high repair costs.
Even with yellowing or burn-in, the display quality is poor, which significantly lowers the evaluation.
Device is faulty
Devices with strange issues such as not powering on, not being repairable, or camera malfunctions are often considered difficult to resell. Even if repairable, the appraisal value may decrease due to repair costs, or in the worst case, the device may not be purchased at all.
Device with water damage
If the indicator inside the smartphone that shows liquid intrusion has turned red, it is considered water damaged, and there is a high risk of malfunction, making it difficult to purchase.
Certain buttons are unusable
If primary buttons such as the power or home button are unusable, it indicates a significant operational problem, which may lead to a drastically reduced appraisal or even refusal of purchase.
SIM unlocking a used smartphone is not temporarily bothersome
Unlocking a used smartphone's SIM lock is not difficult if the correct procedures are followed. However, if you want to unlock a device purchased used, information from the shop where it was purchased or the previous owner holds the key.
Also, after acquiring a used smartphone, don't forget to check its operation, battery, and red-flag risk in addition to SIM unlocking before safely starting to use it.
If necessary, consider smartphone insurance to prepare for breakdowns and problems.
PRODIG focuses on carefully selected used smartphones, and various checks are being considered, with an emphasis on SIM lock status and operational checks.If you want to use a used smartphone with peace of mind and safety, why not look for your preferred device on the official online store "PRODIG" for used smartphones and tablets?
Click here for a list of used iPhone products offered by PRODIG
Click here for a list of used smartphone products offered by PRODIG
新着記事
