iPhone 4 v4.1 02.10.04 Unlock

I would like to unlock my iPhone so I can use a different sim card when I travel internationally to visit family.

I am currently running v4.1 (8b117) with BB 02.10.04

Can anyone recommend a solution that is compatible with this configuration. I still have an older iOS 4 version, so I am hoping that will work in my favor.

Thanks for the support
Steiner

Before going that route, I have to ask: have you talked to your carrier?

In many countries other than the US, the carrier is often willing to unlock the iPhone after you've been with them for a certain period (varies) or paid a fee (varies). If available, a carrier unlock or factory unlock is ALWAYS preferable to a "hack" unlock, because the latter has to be re-done EVERY TIME you update the OS. That really gets to be a right PITA.