the first way is the safe way if you call tmobile pda support they will request unlock code for you for free as long as you have had tmobile more than 90 days or check out this website for another way
http://www.intomobile.com/2008/12/0...-t-mobile-g1-into-an-android-dev-phone-1.html
http://www.intomobile.com/2008/12/0...-t-mobile-g1-into-an-android-dev-phone-1.html