Can I unlock an iPhone 3GS 16gig AT&T for free and forever?

Forever as in can be updated and will still be factory unlocked.

Free unlocking service is not safe. So better you can use any paid unlocking service. To unlock your iPhone 3GS from AT&T network lock visit http://www.simpleunlocking.com/apple-iphone-3gs/rs16wp9/ .Here you can get unlock code with free step by step unlocking instructions at reasonable cost. This is reliable and secure.