If you were unlucky enough to upgrade your Apple iPhone 4 to iOS 6.1 while preserving the baseband to 01.59.00, you must be facing fluctuating "No Service" and "One Bar Signal" bug after using Ultrasn0w which is supposed to work on the older baseband and newer iOS version.

This Apple iPhone 4 + iOS 6.1 + Modem 01.59.00 + Ultrasn0w 1.2.8 combination results in a major compatibility issue which results in cycling one bar of network and then No service every 20 seconds.

UPDATE : There seems to be a bug in ultrasn0w 1.2.8 when used with iPhone 4 having modem 01.59.00 on iOS 6.1. So Pls. do not proceed with following steps until this gets fixed.

Users relying on Ultrasn0w software carrier unlock can now upgrade to Apple iOS 6.1 as it can now be jailbroken using evasi0n and is now supported by ultrasn0w 1.2.8 update, do keep in mind that you must have the baseband (modem) preserved to one supported by ultrasn0w. Follow the guide posted next to upgrade, jailbreak and unlock iOS 6.1 while preserving the baseband.

If you have an Apple iPhone without a working WiFi connection and you are dependent on the Ultrasn0w software unlock, you are stuck in a sort of classic "Chicken or the egg" dilemma - you dont have an WiFi internet connection and you can't use your cellular data network until you unlock your phone by first downloading ultrasn0w via Cydia !!!

Thankfully, we have solutions to install ultrasn0w manually as blogged earlier - however, the trick shared earlier is outdated now and UltraPusher is no longer updated. We can still get things done manually as instructed ahead.

iPhone Dev Team pushed out updated version of Ultrasn0w incrementing the version to 1.2.2 allowing software carrier unlock for iPhone 4, 3GS and 3G running iOS 4.3.2.

The most widely used iOS software unlock Ultrasn0w just got updated by parent iPhone Dev Team to support carrier-unlocking on any baseband later than 05.13.04 for iPhone3G/3GS owners. This unlock is interestingly using the exploited AT+XAPP command security-hole which was actually plugged-in by Apple but it turned out that the very first iPad firmware 3.2.2 has baseband version 06.15.00 which is still vulnerable to AT+XAPP exploit and since the iPad baseband is built for the exact same baseband-chip as the iPhone3G/3GS what we have is an exploit with a carrier unlock for these devices. In simpler terms iPhone 3G/3Gs owners can unlock their devices running iOS 4.1/4.2 but there are some risks as posted next.

If you have Wi-Fi or internet connectivity on your iPhone it's pretty easy to install carrier unlock Ultrasn0w via Cydia on your device, however, things get complicated if you have no internet or Wi-Fi available on your iPhone leaving you with no choice but to install Ultrasn0w manually which require working with iPhone file-system and file-permissions.

Thankfully, we do have a pretty much unknown utility 'UltraPusher' which lets users install MobileSubstrate and Ultrasn0w on their iPhone offline from any windows computer, all you need to do is to connect your phone via USB and let UltraPusher inject the required files automatically.

iPhone Dev Team's carrier unlock Ultrasn0w is now updated to v 0.92 fixing the cosmetic missing carrier name bug on devices with firmware 3.1.X having baseband 04.26, to install the latest Ultrasn0w update make sure your iPhone is connected to internet and launch Cydia, it will display the new update from where you can install it.

While iPhone lovers were disappointed that the latest unlock from iPhone Dev Team UltraSn0w does not support unlocking the new Apple iPhone 3G S, a good news is here - the author of the original iPhone unlock exploit and Bootloader 4.6 cracker "GeoHot" has made significant progress towards exploiting the new iPhone 3G S bootloader bypassing the sigchecks which could potentially result in an iPhone 3G S jailbreak and un

Latest version of the popular iPhone jailbreaking utility PwnageTool from iPhone Dev Team is now available for public downloading, the new PwnageTool v 3.0 supports jailbreaking the new iPhone firmware 3.0 on all versions of iPhone and iPod Touch devices except the new iPhone 3G S, The Dev Team also warned not to use PwnageTool 3.0 if you are using yellowsn0w and wait few more days until new iPhone unlock UltraSn0w is available.

Contrary to everybody's expectation it now seems that UltraSn0w is not able to unlock iPhone 3G S as of now, but if you have any other version of iPhone/iPod Touch with any baseband and firmware the new PwnageTool will work.

Jailbreak and carrier unlock for latest Apple iPhone 3G S seems to be here, the famous iPhone Dev Team has now released an video demo displaying successful carrier unlocking on official 3.0 firmware which means it should be able to unlock iPhone 3G S which comes pre-loaded with same operating-system version, the DevTeam has decided not to reveal the exploit named UltraSn0w until iPhone 3G S finally hits the stores tomorrow.

The iPhone Dev Team also announced that official updated versions of PwnageTool and QuickPwn working with iTunes 8.2 for jailbreaking iPhone 3.0 firmware are under development and will get released soon.