how to unlock iphone 1g

Hello, My uncle gave me his Iphone 1g mobile phone which he bought from the US and to be able to work it with another sim card like vodaphone or airtel, can anyone tell me how to unlock it? The technical specifications of iPhone 1g is below:

Specs

• Size - 115 x 61 x 11 mm
• Weight - 135 g
• Screen - 320 x 480 px
• Networks - 850 / 900 / 1800 / 1900
• Bluetooth - Yes
• Camera - 2 Megapixels
• MP3 Player - Yes
• Memory - CardSD
• Java - SupportNo
• Radio - SupportNo

Just cause it's the same carrier, doesn't mean it can use different SIM cards from the same carrier. I think this works with Blackberrys too...You can only use the SIM card that the phone was activated with (unless they extended that to phones of the same type).

You can try unlocking 1g iphone 2.02 firmware. Follow the tutorial given here.