sorry to disappoint u guys but i guess d prob is not d sim its d phone...i am based in india and i had d same prob but i managed to correct it..go to settings-time n date and then u wud see that auto update of time is on and time zone is set to gmt or watever..uncheck auto update and adjust ur timezone n do not check back auto update..just click save...close conversations and open them again d time wud be fine )