Since the last week video came from the unknown hacker who claims that he has found the bug in iOS 5 systems that could allow users to unlock their iPhone 4S without any jailbreak ultrasn0w and Gevey SIM interposer. Every other person who blogs about iPhone tips and tricks has posted the same line on their blog that iPhone 4S can be unlocked, even without knowing about the actual process and trick, which enable them to get temporary unlock on the device.
Earlier today, we have reached the MuscleNerd the member of the iPhone Dev team to lead some light on this method, he clearly mentions in the series of twitter replies that trick only works for the couple of seconds, and the unlock status of iPhone 4S only longs for few minutes, because the unlock trick bases on the TMSI of the device, and the unlock status only longs until the device does not refresh the TMSI to get new to protect the users.
As far as I know about the pros and cons of this TMSI method, every time we start our iPhone 4S / iPhone 4 it checks for the TMSI (temporary mobile subscriber identity) and caches it locally on the device before sending the IMSI to the carrier for process. Here is the little excerpt about TMSI:
The TMSI is a 32-bit number (4 octets) that is temporarily assigned to a MS and is used on the network in lieu of the IMSI. It is designed to protect the privacy of the subscriber and prevent the IMSI from being discovered. The VLR will assign the TMSI to a MS when it registers in that Location Area. The network may also require the VLR to assign a new TMSI to a MS periodically or even every time it completes a transaction. The TMSI is stored on the SIM card. The TMSI is always assigned when in cipher mode. (traffic is encrypted). Click here to read more about authentication and encryption.
In this sketchy iPhone unlock method. User can only get the signals from another carrier for few couples of seconds on their device, but as soon as the device again checks for the TMSI, the user loses the signal again and requires to perform steps again. So now after this information from the jailbreak community, we suggest our readers to stay away from this kind of tricks on their device, and avoid going with any website offering unlock for money. We recommend you to wait at least for the official statement from the iPhone Dev Team, the team that, firstly, introduced the unlock for the iPhone.