HELP!! 1st GEN 4GB APPLE IPHONE UNLOCKED?

hey guys, i recently purchased the 3g version of the iphone, and it works great. my old iphone which is the 4gb 1st gen is just rotting now on my desk. i wanted to unlock my old iphone. just to reming you guys that my iphone has the 2.0 firmware on it. what i did was i downgraded its firmware to 1.1.4. and success it did. here comes the confusing part, i unlocked it with ZIPHONE.ORG 3.0 version. i followed step by step instructions and success i made the phone unlock with 2 additional icons INSTALLER.APP, and the zipphone log.The phone did not crash, it's running perfectly, WI-FI is up, you can go on youtube, browse on safari, and email. but my problem is that, did i successfully unlocked it? because I have no bars on the iphone, it clearly states NO SERVICE, and i was trying to use my GO-PHONE AT&T pre-paid sim car, it did not work, i tried my new AT&T sim from my 3g iphone and it did not work. IS IT UNLOCKED? DO I HAVE TO USE ANOTHER SIM, THAN AT&T? any help will be helpful. thanks