Error «Invalid MMI code» can occur in a number of cases. But most often it appears when you send a USSD-request. For example, the reason may be an error in the request or a problem with the SIM card. In this article we will consider all options to solve this problem.
A mistake in the USSD-request
This option should be checked first. Even if you have already used the code for the query, go to the official site of your mobile network operator and make sure that the service you want to use is active. For example, it could be move to archived, or the combination may have changed.
Also, make sure you make no mistakes in the set. If necessary, consult the call-center.
Poor network coverage
This error often occurs in the case of a request sent from locations with poor 3G or 4G network coverage. In this case it is necessary to try switching to 2G mode. Usually it can be done the following way: go to «Settings» -> «More» -> «Mobile networks» -> «Preferred network type»:
Also, try to restart the phone. If, after the abovementioned steps the error is still there, you might have a problem with the SIM card.
The problem with the SIM card
Sometimes such problems may occur due to the problems with the SIM card, especially with older SIM cards. The only way to solve the problem is to replace the SIM card. Fortunately, this can be done in 5 minutes in almost any office of your mobile network operator for free.
If you have any further questions, please do not hesitate to contact our help desk!