How to reactivate my iphone 2.2.1 3G after OS 3.0 was downloaded and got locked??

[abbaiah]

Hi!
Few days back i downloaded OS 3.0 to my apple iphone 3G through my apple Macpro laptop.After completion of downloading,i saw that the iphone was locked showing a Wire/Plug with itunes emblem on the iphone screen with a message stating that "Only Comapatible SIM card from a supported carrier may be used to activate iphone".Now i am unable to open the iphone.The iphone 3G was bought by me during February 09 from an authoried shop in an unlocked condition and i was using the same with any SIM card.In USA i was using the phone with AT&T SIM card and after i downloaded 2.2.1, the carrier was disabled and i was advised to use the SIM card from the supported carrier which i found out to be O2 of UK.Then i unlocked the same through an unlockable SIM and was again using AT&T SIM card.Recently I was using AIRTEL SIM card.Few days back when I downloaded OS 3.0,it got locked and i am unable to open the iphone.After downloading I noted ICCID number was also changed. Please guide me.
Abbaiah

[Plan B]

jailbreak it

[hawk95]

You can unlock your 3g first with redsnow to jailbreak it then go in cydia download ultrasnow to unlock it

[blkcadi]

^ yup

[Plan B]

You can unlock your 3g first with redsnow to jailbreak it then go in cydia download ultrasnow to unlock it

What? You mean jailbreak it first with redsnow then go in cydia to download ultrasnow

[albrevng]

Technical Definition of Jailbreak:
The iPhone and iPod touch hack that allow users to gain access to the entire Unix filesystem. In Unix terms, this refers to changing the root of the directory tree to /.

Understandable Definition of Jailbreak:
A hack that gains access to areas of the iPhone or iPod Touch that users aren’t supposed to mess with. Typically, this is an immediate prelude to either installing cool programs, unlocking the handset for use with another cellular network, or both.
Through jailbreaking, you are able to add additional applications to your iPhone or iPod Touch. It allows you to do so by adding an application called Cydia (firmware 2.x) or Installer (firmware 1.1.4 and below) to your iPhone or iPod Touch. It also also modding (changing) of your iPhone/iPod Touch application icons, wallpaper, dock, status bar, chat bubbles, weather backgrounds, keyboard….etc. For more information on the Cydia or Installer applications.

If you don't know about jailbreaking, you're in the wrong jailhouse:-)