Iphone 4 jailbreak question

[Jamsim]

hey guys i just wanted to know what program did you use to jailbreak your iphone 4 4.2.1 (8C148) with baseband 03.10.01?
And also if i was to jailbreak it, would it mean i could use it with another carriers SIM card? or would i have to unlock it?
Thanks in advance

 

[rookhoe]

Use greenpois0n. There a couple threads going in the active threads section.

 

[Bhinton]

You can jailbreak with the latest greenpoison but 3.10.01 cannot be unlocked yet