jailbreaking iPhone 3 running iOS 4.2.1

[cheyennedesire]

some guy my boyfriend works with wanted us to try and unlock his phone from AT&T to T-Mobile. I know how to do it and everything, my problem is that I can't find a jailbreak that will work with the iOS build that it's on. I currently have redsn0w on my computer, because I have an iPhone 4 that I mistakingly updated to 5.1. But when I tried to jailbreak the iPhone 3 with redsn0w, it didn't work. So if anyone could suggest ways to jailbreak it, or even ways that I can get 5.0.1 to work on it, that would be appreciated.

I don't need to unlock it, but if I could, that would be very beneficial.

 

[Jmills87]

You can jailbreak iPhone3G on 4.2.1 with Redsn0w, there's no way to install 5.0.1 on it though since 4.2.1 is the newest firmware available for the 3G.

Unlock will depend on what baseband the phone is running.