Sim 1 Not Allowed on Samsung S21

Sim 1 Not Allowed on Samsung S21 – Comprehensive Guide to Fix.

Comprehensive guide to resolving the SIM 1 not allowed on Samsung S21.

I was excited to get my hands on the dual-SIM Galaxy S21 smartphone. Everything was going smoothly.

Suddenly, my mobile internet connection started to drop for a few minutes at odd periods, which was quite inconvenient. So, I tried to find a way of coming across a solution. To make matters worse, the error notice “SIM 1 Not Allowed” began to appear, and my SIM card was no longer connected to the network. Fortunately, it still worked in the SIM 2 slot.

I executed some research and tried a lot of solutions to fix the Sim 1 Not Allowed on Samsung S21 issue.

Finally, I discovered some successful solutions!

So, I thought I’d share my experience and solutions with all of you.

Why Do You Get an Error message “SIM 1 Not Allowed”?

If your Samsung S21 shows a “SIM 1 Not Allowed” error message, this indicates that its SIM card may be defective. The error could be due to several factors including blocked SIMs or carriers locking one of its slots (this could happen if you bought your phone from AT&T, Verizon, or T-Mobile who lock one SIM slot to ensure their services instead of switching).

Software glitches, hardware failures, or accidentally modified settings could also present themselves as issues on some phones; users who aren’t the original owners may also run into difficulty paying their payments on time or are otherwise responsible.

How to fix Sim 1 Not Allowed on Samsung S21?

Although this issue may appear complex, it’s easy to address.

Checking your SIM card, network coverage, and device restart are among the many steps that could help resolve it as are updating software on your phone and contacting carriers to unblock SIM.

If none of these alternatives work, you can take your phone to a Samsung service center for assistance.

Solution 01: Check Your SIM Card

First, double-check your SIM card by inserting and verifying it properly in another phone, making sure it hasn’t been damaged or broken. If it has, contact your carrier immediately so a new card can be issued if required; or just take it out and insert it into another device to see if damage exists.

Solution 02: Check Network Coverage

If your SIM card hasn’t any issue, you could check the network coverage in your location. This error may occur if your device is not receiving a strong network signal. Contact your network provider or use their coverage map to check network coverage.

Solution 03: Restart Your Phone

This error message is sometimes generated by a software problem. In this situation, restarting your phone may assist in resolving the issue.

To restart your Samsung S22,

  1. Press and hold the Power button and Volume down button simultaneously until the power menu appears.
  2. Then, tap on restart. When you tap Restart, your phone will restart.

Solution 04: Reset Network Settings

Resetting your Galaxy S21’s network settings can frequently resolve this issue by restoring all configurations to their default condition.

Note: This process will clear away all current settings, including saved Wi-Fi networks and Bluetooth pairings

To restore your network settings, follow these steps:

  1. Launch the “Settings App”
  2. Scroll down and tap on “General Management”
  3. Select “Reset”

Inserting image...

  1. Select “Reset Network Settings”
  2. Tap on “Reset Settings”
  3. Tap on “Reset” to Confirm.

Once completed, switch off the device. Insert a SIM card in SIM 1 of your phone to test if this solution has helped resolve any problems that have arisen.

Solution 05: Software Update

There’s always the risk that your Samsung phone is using an outdated software version, so be sure to check for updates regularly. Otherwise, serious problems could ensue should it not run the latest software version.

To check software updates, follow these steps:

  1. Launch “Settings”
  2. Tap on “Software Update”
  3. Go to “Download and Install” (If one is available, download and install it)

Solution 06: Check the IMEI Status

One of the primary sources of this issue is a blacklisted IMEI. Before taking steps to unblock it on your Samsung S21, ensure that its SIM 1 slot IMEI has not been blocked first by checking its IMEI status. Here’s how you can do it.

After this step is complete, you should access any database website to search your IMEI number.

Follow these steps for identifying a mobile device’s IMEI status:

  1. Dial *06# to obtain the IMEI number of your device.

  1. Once you know your IMEI number, visit an IMEI database website to check its status.
  2. Enter your IMEI number into the website and submit a request to check its status.
  3. The website will then display device information such as brand, model, serial number, and whether it has been reported lost or stolen.
  4. If a device has been reported as lost or stolen, this can inhibit access to certain networks and necessitate reporting it as such. If this is the case for you, contact authorities immediately and report the lost/stolen device as quickly as possible.

  1. Your device could have been blacklisted by its carrier. In such a situation, reach out to them to find out the reason.

Solution 07: Contact Your Carrier

If your smartphone was purchased from a carrier, customer service can verify whether its SIM slot has been blocked and unblock it so you can use any SIM card in that slot without issue.

Solution 08: Contact a Samsung Service Center

If none of the above solutions worked, your Galaxy S21 most likely has a hardware failure.

To test this, do not perform any actions such as resetting the device or emptying the cache. Go to the nearest Samsung service center as soon as possible. Then leave the problem to the specialists.


Have you fixed the “Sim 1 Not Allowed” bug on your Samsung S21? Share your success story or any other helpful tips in the comments! Your experience could be the solution that someone else is looking for.

If you need any assistance with this guide or have any queries, feel free to leave a comment below and we are more than happy to assist you.

Let’s troubleshoot together!


Q1: Why is my phone showing SIM 1 not allowed?

While that might impact older Android phones and gadgets like Kindles, SIM card faults on contemporary Samsung phones are probably caused by configuration problems. The first thing users should do if their Samsung phone displays the “Sim 1 Not Allowed” issue is to make sure their SIM card is inserted correctly.

Q2: Why is my SIM 1 slot not working?

It’s possible that the SIM card is filthy or broken, or that you did not put it in the tray properly.

Q3: How do you fix Sims 2 not allowed?

Take the subsequent actions:

  1. Give your phone a restart.
  2. Put the SIM back in.
  3. Verify whether the SIM is active.

If nothing resolves, get in touch with your network provider.

Read more :

Samsung S22 Not Receiving MMS Messages.