If you want to check your Mobile balance or data balance by USSD just check below details.
Vodafone:
To check Vodafone balance dial : *146#
To check Vodafone data balance dial : *111*6*2#
To know various offers and call history dial : *111#
To know your own mobile number dial : *777*0#
Airtel :
To check Airtel balance dial : *146#
To check Airtel data /gprs / internet balance dial : *123*11#
To know your own mobile number dial : *141*1600#
Tata Docomo :
To check Tata Docomo balance dial : *111#
To check Tata Docomo data balance dial : *111*1#
To know your own mobile number dial : *580#
Idea :
To check Idea balance dial : *131#
To check Idea data balance dial : *131*3#
To know your own mobile number dial : *789#
Aircel :
To check Aircel balance dial : *125#
To check Aircel data balance dial : *126*1#
To know your own mobile number dial : *888#
Reliance :
To check Reliance balance dial : *367#
To check Reliance data balance dial : *367*3#
To know your own mobile number dial : *1#
Tata Indicom :
To check Tata Indicom balance dial : 12527
To know your own mobile number dial : N/A
Uninor :
To check Uninor balance dial : *363*4# or *222*2#
Virgin :
To check Virgin balance dial : *111#