Nov 28, 2010 11:08 GMT  ·  By

An unlock for iOS 4.2.1 is almost ready to go, signals iPhone Dev Team member Musclenerd, via Twitter. Apparently, Apple tried to block their ultrasn0w unlock tool via “aggressive compiler optimization,” but the Team was able to crack it and is gearing up to release a new version that will do the trick for iOS 4.2.1 users, albeit only for those wielding an old-generation handset.

“Finally got ultrasn0w working fully on 4.2.1,” Musclenerd writes on Novemver 27. “Apple inadvertently(!) broke ultrasn0w via aggressive compiler optimization,” the hacker explains.

In a separate note that hit the micro blogging service just minutes ago, Musclenerd adds: “When we update ultrasn0w today, 100's of thousands (maybe millions?) will see red badge. Trying to make it safe for all.”

Ultrasn0w is a hack tool developed by the infamous iPhone Dev Team whose software is generally the most reliable, and always free to download and use.

Unlike redsn0w, which provides a “jailbreak”, ultrasn0w delivers the much-craved-for carrier unlock which permits iPhone users to switch operators as they please. Apple generally enforces restrictions so that iPhone users are tied to one, or two carriers in a certain territory.

The updated ultrasn0w utility will only work on iPhone 3G and 3GS handsets with a baseband of 05.15.04, according to reports.

iPhone 4 uses a different baseband, yet the Dev Team does not want to put the unlock on hold to get all devices on board. An iPhone 4-compatible version is likely to emerge soon.

The Dev Team is best known for its PwnageTool utility. A Mac-only program, the tool can be employed to both jailbreak and unlock an iPhone. PwnageTool is yet to be updated to support Apple's latest firmware update.

As of this writing, the Team’s official blog was down, indicating huge interest in the unlock tool.

This article has a purely informational purpose and doesn't, in any way, suggest that you should hack your Apple device.

Using hacks may render your device unusable, or may reduce the quality of your experience employing the respective device.

If you choose to download and install jailbreak tools, you will do so at your own risk. Unlocking / jailbreaking your iPhone / iPod touch / iPad / Apple TV may violate your warranty or the EULA with Apple and / or your cellular-service provider.