Press *#272*HHMM# for android 2.1, or *#272*IMEI# for android 2.2 in the dialer, where HHMM is hour and mins in 24hr format of the current time

Singtel users choose SIN

Starhub users choose STH

M1 users choose MM1

for naked sgs rom, choose XSP

Select your option and click the install button to complete the setup.