Samsung Galaxy S21

Sim 1 Not Allowed on Samsung S21 – Complete Guide to Fix

Complete guide to fix SIM 1 not allowed error on Samsung Galaxy S21
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Samsung Galaxy S21 comes with dual SIM support. However, a lot of users are experiencing problems with the SIM 1 slot in this device.

In Galaxy S21, users have reported on the Samsung community and Reddit that there was an error called “SIM 1 Not Allowed” when they used the device. Some of them have tried several solutions to this, like clearing the cache, resetting network settings, changing SIM cards, and so on. But none seemed to fix the issue (for some users). 

But unlike them, you have come to read this guide. Which means you will be able to fix SIM 1 Not Allowed on Samsung S21. 

First, we will go through the possible reasons for the “SIM 1 Not Allowed” issue. Then, we will tell you what you should do to get rid of this error on your device.

Note: Solutions in this guide will work on any Samsung Galaxy S21 model (S21, S21 Plus, S21 Fe, and S21 Ultra models.)

Editor’s note: We created these instructions using a Samsung Galaxy S21 running Android 12. Depending on your device’s software version, some steps and menu positions may look slightly different.

In a hurry? Watch the video!

Why Do You Get SIM 1 Not Allowed on Samsung S21?

Why do you get sim 1 not allowed on samsung s20 or s21

SIM 1 not allowed error usually occurs due to the IMEI being blocked or when a carrier locks the SIM 2 slot on your Samsung S21. However, configurations in the network settings, system bugs/glitches, and hardware failures all contribute to the SIM 1 not allowed error.

If you are not the first owner or the user of your Galaxy S21, then there is a chance that the IMEI of your phone’s SIM 1 slot has been blocked by a carrier. If you ask why a carrier locks the IMEI number, then it can be due to overdue payments, unauthorized activities, or even going against its policy (Like selling the phone to another person). 

The second reason is applied if you purchased the device from a carrier (In the USA like Verizon, AT&T, Sprint, T-Mobile, etc.) These carriers usually lock one SIM slot to stop people from using another SIM card (a.k.a using another network) on their device. Since you cannot access the other SIM slot, you will be left with their network, thus forcing you to use their service. Which most people don’t like much.

If we talk about configuration issues, there can be accidental settings that you might have turned on (Like disabling the SIM slots) or turned off (Like the network recovery). Although you haven’t done anything to the network and SIM card settings on your Galaxy S21, software updates, and third-party apps can also cause the SIM 1 not allowed error.

Lastly, hardware issues are not very rare for this smartphone. It is because some users have brought their smartphones to the Samsung service center and the result was they claimed the warranty due to hardware issues with the SIM 1 slot. 

So these are the reasons why you are getting SIM 1 not allowed error on your Samsung S21. But don’t worry. Although you might feel this is a hard-to-solve problem by reading the reasons, it is not that hard to fix.

Fix 01: Reset Network Settings

There are still a number of users who solved this problem by resetting the network settings on their smartphones. Therefore, it is worth giving this solution a try.

Here is how to reset the network settings on your Samsung Galaxy S21:

  1. Open Settings.
  2. Tap on General management.
  3. Under general management, tap on Reset.
Reset option samsung
  1. Then, Tap on Reset network settings.
Reset network settings
  1. Confirm and proceed to reset network settings.

Once it is completed, power off the device. Then insert a SIM card into the SIM 1 slot power on your phone, and see if the solution works.

Fix 02: Change the SIM Card in SIM 1 slot

Although we didn’t mention earlier, sometimes faulty SIM cards can also cause to SIM 1 Not Allowed issue. Therefore, use a paper clip or the SIM tool you got with your Galaxy S21 and take the SIM tray out. Then, clean the surface of it and use a working SIM card insert it into the SIM 1 slot, and insert the SIM tray into the phone again. Then, power on the device.

If you still get the SIM 1 not allowed error even after doing that, then there is a problem with the IMEI of the SIM 1 slot or the carrier has blocked the device from using the SIM 1 slot.

Fix 03: Check the IMEI status 

Imieinfo website
Imie info website

Before you are going to unblock the IMEI on your Samsung S21, you need to check the IMEI of the SIM 1 slot to make sure whether it is blocked or not. And here is how you can do that.

There is an online tool you can use to check the IMEI called According to them, they have a large database that gets updated every day on the IMEI locking status and many more. However, to check the IMEI lock status, you have to pay a small fee (When we last checked the price, it was 3 USD per IMEI check). Considering how badly you want to figure this out, it is worth giving a try.

Note: We are not affiliated or working together with the IMEI.INFO website. Also, we do not guarantee or take any responsibility for the payments made to that website.

With that being said, here is how you can check if the IMEI of the SIM 1 slot of your Galaxy S21 is locked.

  1. Go to the IMEI blacklist check –
  2. Type the IMEI number of the SIM 1 slot. You can get the IMEI number by dialing *#06#
  3. Tap/Click on the Check blacklist pro button
  4. Then you will get the payment screen, make the payment, and verify the IMEI.

If you get something like this, it means the IMEI of the SIM 1 slot of your device is blocked by a carrier, you can also see which carrier has blocked the IMEI. You can use that information to contact them and get the IMEI unblocked.

Fix 04: Contact Your Carrier

If you purchased your smartphone from a carrier, then you can contact their customer support and ask them to check if your device’s SIM slot is blocked. If so, you can unblock the SIM slot from their end and use any SIM card in that slot to use without any problem.

Fix 05: Go to Samsung Service Center

If none of the above solutions worked, then chances are high that there is a hardware failure on your Galaxy S20/S21.

To check this, without doing anything like resetting the device, clearing the cache, etc. Go directly to the nearest Samsung service center. Then let the experts take care of the issue.

Wrapping Up

Even though the SIM 1 not allowed error can be caused by various problems, not all of those are in your hands to solve. That is why we gave all the solutions to you, to try and get the SIM 1 slot working.

If you have any questions regarding this guide or need help, leave a comment below. So we can help you from there.

Have a nice day!


The founder of and the tech nerd of the team. He is specialized in Android/iOS development and web development.

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