Jailbreaking 5.1.1 through Mac

Hi I want to know if it's possible to jailbreak my iPhone 4 to update to version 5.1.1, because I got the iPhone as a present from Canada using the carrier Bell (though I'm in Australia),so there's no way i can use that sim, and Bell says that they do not unlock their phones and told me to use a 3rd party software to unlock it
so does anyone know of softwares that can jailbreak 5.1.1 yet?? Through a Mac!
my current version's 4.3.5

To the best of my knowledge, there is not yet any way to UNLOCK (not the same thing as jailbreaking) a factory-locked iPhone running iOS 5. There looks to be some progress on that front but at present that's where we are.

But I thought u had to jailbreak it to be able to unlock the phone without going through the carrier......so both are two independent things?? I just want to be able to use a foreign sim after updating,so I wouldn't really have to go through jailbreaking is it??

You do have to jailbreak the iPhone first, but they are still two different processes.

I believe there is an untethered (never mind what that means, it's the one you want) jailbreak for iOS 5.1.1, but it still requires that you have carefully preserved a very old baseband -- so for all intents and purposes for anyone remotely close to normal, there's no working jailbreak either.

Have a talk with your carrier about unlocking the phone. Many have adopted much more sensible policies about this and will unlock your phone (without jailbreaking) for you if you've been a customer for x amount of time or if you pay a fee etc.

Well thing is I got it as a present from abroad,so yeah never been their customer
I'll try asking the uncle who sent it to me
Thanks btw