Flight mode
For SIGMATEL S4 Flight mode
click Home Key In on touch screen
then Ur Menu Will Be Opened Change it To normal mode
for other sigmatel
Dial- *#3646633# ,
engineer mode will open
select 'Misc'
then select 'Assert Testing' now your phone will restart,
now u can able to enter menu now change normal mode.
for other mobile just format
don't format or dont flash just
with out sim *#3646633#
you wil get eng menu
option 5 misc
option 6 assert testing
now menu will open
u select dual mode
