My unlocked iPhone originally working well since January has now malfunctioned, allowing incoming calls and texting both directions but no longer able to call out. I cross between the US and Mexico every month and have been successfully switching SIM cards until today. The only thing that I did different this time was while in the US, I switched off Yellowsn0w in Boss Pref and then switched it on again when back in Mexico. I tried reloading yellowsn0w but no luck. Using version 0.9.8 One more thing of interest, 3G data service suddenly appeared, something that you must normally sign up separately for in Mexico. I don't have a plan, just the prepaid card. Any ideas?