Can I downgrade from 4.0.1 to 4.0?

[Andronicus]

I sold my friend my old iPhone 3GS and he took it to the mall to get it unlocked for use on Tmobile. They are telling them if the phone was upgraded to iPhone 4.0.1 then they aren't able to unlock it right now. So, I was wondering if there was anyway to downgrade from 4.0.1 to 4.0 so that they are unable to unlock it???

Thanks for the help.

 

[Juanes108]

Jailbreak and unlock iphone 3GS 4.0.1

Hey man try this website www.iphonedownloadblog.com. I used it to jailbreak and unlock my iphone 3G on OS 4.0.1. Hope this works for you.