I have updated my iPhone 4 (GSM) to iOS 5.0.1 with untethered jailbreak using redsn0w. I didn't unlock because I'm still in contract with the original carrier (Vodafone, here in Spain). I had previously jailbroken (but not unlocked) my phone. Now the phone is jailbroken in 5.0.1 but it says constantly No Service, the name of the carrier does not appear in "Settings", and "My Number" appears as "unknown". So I can't use my phone! Please let me know what I should try. My modem firmware, if that's of any use, is 04.11.08.