Hi guys, I have a carrier locked iPhone 4. I bought it on eBay months ago and it was locked and upgraded to the last firmware (iOS 5.1.1) so I can't unlock it. I took it to a shop that made a BASEBAND DOWNGRADE (they replaced the baseband chip) so I had iPhone 4 with baseband 01.59.00 which I can unlock with Ultrasn0w. It worked for two months until Apple released iOS 6.1 and Dev Team the untethered jailbreak for this firmware. I upgraded my iPhone with a custom firmware created with Sn0wbreeze (so it preserve the baseband) and unlocked it with Ultrasn0w. I found that the signal with iOS 6.1 was very poor, so I downgraded my iPhone to iOS 5.1.1. It worked for a week, than my iPhone showed this error: Restore needed. iPhone cannot make or receive phone calls (http://support.apple.com/kb/TS2430?viewlocale=en_US&locale=en_US). I tried restoring iOS 5.1.1 and also iOS 6.1 but the problem persist. Now I restored to iOS 6.1.3 with tethered jailbreak but the problem still exist. I found that I have NO Firmware modem in Settings -> Info and also if I deal *#06# there is NO IMEI number. I searched on Google but all posts I found are related with NO BASEBAND, NO WIFI AND NO BLUETOOTH. But in my iPhone 4, Wifi and bluetooth still work. I guess that my iPhone is without baseband at the moment, so is there a way to flash only the baseband? I need to flash an unlockable baseband since my iPhone is carrier unlocked. What can I do?