Chosen Solution
I just bought an iPhone 3G and place a new SIM card in it. Now it says no sim card and it won’t let me unlock or shut off my phone. How do I fix this?
do a hard reset press home and power button at the same time til the phone reboots
Use Remote unlocking method to unlock your iPhone 3Gs quickly. It doesn’t requires jailbreaking. This method is available at Mobile-unlocker.com . Here, you need to specify your Network and Country to get unlocking service from them .