Required firmware : 3.0
Required software : redsn0w
Compatible devices : iPhone 2G

Note that this RedSn0w tutorial is for Windows users but I assume the steps are similar on a Mac.

1. Before doing anything, make sure you have the latest version of iTunes and the latest firmware 3.0 installed on your iPhone 2G.

2. Create a new folder on your desktop. In this folder, download RedSn0w as well as the latest 3.0 firmware for your iPhone 2G from our firmware page (make sure you pick the right firmware). Also download the following bootloader files: BL 3.9 and BL 4.6

3. Unzip and launch RedSn0w.

4. Click “browse” and select the 3.0 firmware you downloaded in a folder in step 2.

5. Once the firmware has been successfully identified, click “next”.

6. Select “install Cydia” and “ulock”, then click “next”.

7. Browse for the bootloader files you downloaded in step 2, and click “next”.

8. Make sure your iPhone is plugged into the computer and that it is off. Click “next”.

9. RedSn0w will then guide you to put your iPhone into DFU mode. Hold down the power button for 2 seconds. Without releasing the power button, also hold down the home button for 10 seconds. Without releasing the home button, release the power button but keep holding the home button for 30 seconds.

10. If done correctly, your iPhone should reboot and the jailbreak process should start. This step may take up to 15-20 minutes so be patient.

11. Once this process is over, you will get a message saying that it is “done!”

12. Click the “finish” button and reboot your iPhone. The reboot may take up to 10 minutes so again, be patient.

13. Congratulations, you just jailbroke and unlocked your iPhone 3.0 with RedSn0w.

Discuss in our forum.

sources : iphonedownloadblog.com
HOWTO : Unlock iPhone 3G on 2.2 with yellowsn0w

Required firmware : 2.x
Required software : yellowsn0w
Compatible devices : iPhone 3G

Its finally here, the long awaited software unlock for the iPhone 3G. Dev team has done a great job. So lets get to it, its pretty simple really.

First you need a jailbroken iPhone 3G, you can read our tutorials here on how to jailbreak.

1. After you have jailbroken your iPhone, fire up cydia application installer.
2. Next click manage on the bottom toolbar in cydia.
3. Click Sources
4. Click Edit
5. Click Add
6. Type “apt9.yellowsn0w.com” without the quotes
7. Click Done
8. Click Search back on the main screen of cydia
9. type in “Yellowsn0w” you should see the application come up
10. Click Install -> Confirm and let it install

Reboot your phone with the new sim card installed, goto settings and reset your network settings. Phone will reboot, leave it for 2 minutes, then goto settings turn on airplane mode on, wait 30 seconds, then turn it off, it should start searching for the new provider, you only have to do this once, after that you can just swap the sim cards.

How to Unlock iPhone 3G Free from Mario Dabek on Vimeo.

HOWTO : Unlock iPhone 3G & 3Gs on 3.0 with ultrasn0w

Required firmware : 3.0
Required software : ultrasn0w
Compatible devices : iPhone 3G, iPhone 3GS 

ultrasn0w version 0.9 is out! We believe it solves pretty much all of the various random issues that have been reported. Its features include:

• Works on both iPhone 3G and 3GS
• Works on jailbroken iPhones
• Works regardless of how you jailbroke your device
• 100% Free

1. After you have jailbroken your iPhone, fire up cydia application installer.
2. Next click manage on the bottom toolbar in cydia.
3. Click Sources
4. Click Edit
5. Click Add
6. Type “http://repo666.ultrasn0w.com” without the quotes
7. Click Done
8. Click Search back on the main screen of cydia
9. type in “ultrasn0w” using zero not ‘o’ you should see the application come up
10. Click Install -> Confirm and let it install