Solution for " Connection Problem or Invalid MMI Code "
i have came across the problem of not being able to execute the basic detail commands provided by the operators to check the details.
however i had the same problem and this is what worked for me
just add an comma (,) at the end of the code.
if your code is *123*1#
then you should dial it as *123*1#,
this way i think it blocks the rest of the codes going with it and works properly
this worked for me check for yours
If it helps please say "thanks"