How to fix “Connection problem or invalid MMI code”

I’m sure most Android users have at some point received a message saying “Connection problem or invalid MMI code”. This can sometimes be so frustrating and so painful to deal with. When the invalid MMI error code appears, it simply means that calls and text messages cannot be sent until that particular problem has been resolved.

There are several problems for which the error message “Connection problem” or “Invalid MMI code” appears. The main reason, however, is probably due to service provider issues or issues related to SIM card authentication on your smartphone.

Solution for Connection problem or invalid MMI code

Try to restart your Android device

restart device

The first method you could try and fix the invalid MMI code error message would be to restart your smartphone first. Open in Network Settings. Then simultaneously press and hold the power and start buttons until all the lights on the phone are OFF. The smartphone will vibrate and restart.

Try to modify the prefix code

The other way to fix your Android phone connection problems would be to add a comma to the end of the prefix code. When you modify a prefix code, you will force the operation to run while ignoring any errors. Here are 2 different ways this can be done.

If the prefix code is, for example (* 5424 * 7 #) , you can add a comma on the back to make it look like this ( * 5424 * 7 #) without the square brackets.

You can use the + sign after the * to make it look like this (* + 5424 * 7 #) without the square brackets

Try to activate radio and activate IMS over SMS

activate radio and activate IMS over SMS

  • Open in bookmark
  • Type * # * ## 4636 # * # ** There is no need to press the submit button as the service automatically appears after you finish writing the code.
  • Tap on the device info or just on the phone info
  • Click on Run Ping Test
  • Press the “Turn off radio” key and your Android will restart.
  • Click on Restart

Try to check the network settings

Manually select your network operator

  • Open in Settings
  • Click on Network Connections
  • Hit on mobile networks
  • Click on Network Operators and choose the wireless provider after the search
  • Log in once again for another 3-4 tries before you can start working again

You can read the solution for not registered on network error or read Unfortunately, the process com.android.phone has stopped which is probably a solution to your problem.

Any questions you have regarding the error message “Connection problem or invalid MMI code” you can leave it in the comments.

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