Iphone 4 : IOS 5.0.1

previously i had baseband 3.10.01 and ios 4.2.1.

i jailbreak and unlocked it but then installed h1siri and it didnt work so i upgraded the ios from 4.2.1 to 5.0.1 and got stuck with "need sim to activate". Iphone 4

Please let me know how to jailbreak,hackactivate and unlock without a need of sim. the carrier is at&t.

If you upgraded your iPhone 4 to 5.0.1 and didn't block the baseband upgrade, you are unfortunately out of luck. You mentioned what your baseband was before you upgraded, can you let us know what it is now? If it's the iOS 5.0.1 baseband, you cannot unlock at this time.