Apple iPhone 4 iOS 5.1 Unlock?

[FlashX007]

Hey I recently jail broke 2 iPhones. I want to unlock both. They are both iPhone 4 8GB with 5.1.1 iOS. I am wondering what unlocking choices are available.

My current baseband for both of the phones is 4.12.01 I believe correct me if I'm wrong.

Also if it's unable to do so should I downgrade?

 

[Dialexio]

You can't use ultrasn0w, since that requires baseband 01.59.00. (And no, you can't downgrade your baseband past 04.12.01.) The GEVEY Ultra and Rebel Sim card don't boast compatibility with baseband 04.12.01, so that's out of the question as well.

The only available option appears to be the "official" IMEI unlock, where you give a website some money and your IMEI for entry into Apple's list of unlocked iPhones. (Make sure the website is trustworthy, since your IMEI is pretty sensitive information… On the top of my head, I know http://cutyoursim.com/ is legit.) This "official" unlock is pricey but it lasts forever, regardless of jailbreak status.