Invalid MMI Code error is found on dual Sim smartphones, such as the Samsung Galaxy S Duos. Usually you will see this error when you are about to check your account balance, Recharging, performing any function designed by your Sim service provider, or Topping up like adding a voucher to run a USSD code. Today we will show you how to Fix Connection Problem or Invalid MII Code.

Method 1: Fix Connection Problem or Invalid MMI Code
To Fix Connection Problem or Invalid MMI Code on Samsung Galaxy device, this method requires you to simply enter into device information mode and activating Radio to Turn on IMS over SMS.
To Enter information mode :
- Dial *#*#4636#*#* in the dialer
- Navigate to Device/Phone Information
- Click on “Run Ping Test “
- After the Ping test is performed
- Click on “Turn Off Radio“
- Next, click on “Turn on SMS over IMS“
IMS :IP Multimedia Subsystem
IP :Internet Protocol
SIP:Session Initiation Protocol
While the setting is off, SMS is sent or received over a period of 1x(times), the circuit-switched connection
Finally reboot the system.
Method 2: Check Network Settings
- Go to “Settings”
- Then select “Network Connection”
- Followed by “Mobile Networks”
- Then, “Network Operators” (at&t, Jio, Airtel, Vodafone or Verizon, etc) and select wireless provider during the search
- Connect again for another 3-4 attempts before it starts working again
Method 3: Restart the Android Device
The best way to fix an invalid MMI code would be to restart the smartphone.
Press Power button to reboot your Android device, all you must do is press and hold down the Power button for a few seconds. A menu will appear asking what action you would like to take. Tap on the option that says Reboot/Restart and your phone will reboot instead of turning off.