Fix Invalid MMI Code Issue in your Android Smartphone

While using your phone, there is a lot of information you might need from your network provider, so take your talk time balance, as an example. To know such information you are required to dial a certain number. These are nothing like regular phone numbers and typically have a star (*) at the beginning and hash (#) at the end. These are collectively called the Man-Machine Interface (MMI) code. They are useful for getting different kinds of information. 

However, they may not always work. Android users often get the message “invalid MMI code” when they dial one. Sometimes, it might work after you try again. But, what if it doesn’t? That’s a problem that is quite commonly faced by people. Certain solutions are available to you in such a situation. So, read on to know more.

Why does this happen?

If you see this kind of error even after dialing a valid number, you might wonder why. There are a few reasons that can be behind this problem. However, the biggest explanation for it is that there are some errors in the carrier itself. It may also be caused when there are some issues with the authentication of your SIM card. Also, you’re more likely to face it if you’re using a dual-sim phone from what it seems.

How do you fix this problem?

If you get the “… invalid MMI code” message after dialing a valid number. You’d want to stop it. For all users who are facing the same, there are some simple methods, you can try for this:

  • Restart your Phone

When it comes to different types of errors in your phone there can be a single solution. Simply, switch off the phone, wait, and then turn it back on. There are so many other issues that this has helped you solve. Maybe it will prove to be beneficial in this case as well. 

Many people are suggesting on the internet to try out this step. Further, you may not know if this easy hack is going to work or not. So, there is only one way to be sure about that, apply it. Also, from what it seems, you might have to do this more than just once. If the problem persists, there’s nothing to worry about as there are other methods as well.

  • Make sure the Network Settings are right

It might be the case that there’s some problem with the network settings of your phone. To select the network connection in your settings, you’ll find the option of mobile networks. Select that and check whether the right network operator has been selected. If not, change it to the correct one and now try dialing the MMI code. If it still shows the error, try this method again a few times.

  • Add a Character to the Prefix Code

Here is another solution that you can see people suggesting on the internet. You simply have to add another character to the end of the prefix code. Add any character, let’s just say “&”, after the hash. Again, you never know if this will work and might want to find out.

  • Switch to Safe Mode

In case you didn’t know, some apps on your phone might be causing connection issues. This can cause it to show an invalid MMI code when you dial one. Now, you might not necessarily want to remove those apps. In that case, you don’t need to worry at all. You can have both, the apps and the solution to this problem. All you need to do is to switch your device to safe mode. This will stop all those applications that were not pre-installed on your phone. Try dialing the MMI code after this and see if it works.

  • Switching on the Radio

This might be a lesser-known solution, but can be quite effective for this problem. So, what you have to do is turn on the radio first. Then, go to the device information on your phone. Select the option of running a ping test. After it’s done, turn the radio off and then turn on IMS over SMS. Lastly, you have to reboot your phone. Hopefully, it would stop showing the “invalid MMI code” error. From what it seems, this method is quite effective as a solution.

  • Change the Network Speed

Are you in a location that has a low signal? Then, it might cause the phone to show the MMI code you dial as being invalid. To fix this, go to the network settings and change the network type. Reducing the speed might improve the signal level. Now, try dialing the MMI code.

  • Talk to Tech Support

Lastly, if none of the above-mentioned options works, you have only one left. You must sort the issue directly by calling your network provider. They will surely help you out in fixing the “invalid MMI code” problem.


Android phones often face the error of “invalid MMI code”. This problem shouldn’t be ignored and you must take essential steps to solve it. There are different methods to do that and all of them have been mentioned above. At least one of them will surely work in your case. Hopefully, you won’t be facing this error for much longer.

Maria Colombo
Maria Colombo
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