Docomo :  *580#

Airtel :  *121*9# OR   *140*6575#  

Reliance :  *1#

Vodafone :  *555# OR *777*0# OR *#1345# OR *#100#*

BSNL :  *1#

Idea :  *789# OR *1# OR *123#

Aircel :  *888# OR *1#

Virgin Mobile :  *1#

Videocon :  *1#