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When I put in my SIM card the phone shows that is has signal, but when I try to make a call it is not going through. I tried entering a service code like *120# for balance of my account and it's saying "connection problem or invalid mmi code" - what's wrong?

ha14
2012-12-26 17:13:03
nice suggestion
Vishal Srivastava
2012-12-08 07:22:51
This has happened with me when I bought a new SGY. New devices might not be compatible with Older SIM Cards. Your device might not support the older SIM. Buy a new SIM or ask your service provider for a new SIM. Although I don't know why it happens that way, but it surely happens as it happened with me.
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susendeep dutta
2012-12-07 16:45:27
Check if any recent app is installed is causing any problem by going to safe mode -http://www.howtogeek.com/130327/how-to-boot-your-android-phone-or-tablet-into-safe-mode/If you can make calls in safe mode,then the above fact justifies it and then try removing that app.If this doesn't helps,backup your data and factory reset your phone.
Douglas Mutay
2012-12-06 14:30:30
Is your sim card registered???
ha14
2012-12-06 12:03:20
try this *100*2#,