I have received hundreds of inquiries on how to unlock the iPhone 3G ever since I have posted a picture of my iPhone 3G running on Smart network. Technews bought the iPhone 3G in Hongkong already unlocked and to my knowledge, there is no way as of this posting to software unlock the iPhone 3G.
There are however other ways in order for you to use other providers in your iPhone 3G.
I have used a Gevey SIM to unlock other iPhone 3Gs in the office. This device came from my source in Hongkong. This is similar to the Turbo SIM solution but safer. While the Turbo SIM requires you to cut your SIM, the Gevey SIM would work by just placing your SIM on top of it.
I used a 16GB iPhone 3G from Globe, here are the steps:
1) Open the Gevey SIM. The Gevey SIM is inside the anti-static plastic. It looks like a thin film with IC on it.
2) Place it on the SIM slot of the iPhone 3G. It fits perfectly but other iPhone 3G units that I tested need to be taped so that he Gevey SIM would not move.
3) Put the unsupported SIM on top of the Gevey SIM. Since the SIM slot has a guide, you won't go wrong in this step.
4) Insert the SIM in the iPhone 3G and turn it ON. Now you can see that my iPhone 3G is using the SUN network :).