While most of the world was busy rocking in the New Year with the Jonas Brothers and Ryan Seacrest, I and a million other geeks around the world were frantically refreshing the iPhone Dev Team’s Blog in hopes that the long awaited software unlock for the iPhone 3g would be released.
When Apple released the 2.2 firmware for the iPhone, they also updated the baseband (modem firmware) from version 2.11.07 to version 2.28.00. Since YellowSn0w was originally built on the 2.11.07 baseband firmware, the Dev Team strongly recommended against updating to 2.2 (and in turn baseband 2.28.00) if you wanted to use their software unlock upon its release.
On New Year’s Eve, however, the Dev Team began posting cryptic messages that were translated to show that they had successfully hacked the 2.28.00 baseband as well and would be releasing YellowSn0w specifically for that baseband instead of 2.11.07.
From a compatibility standpoint, that sounded like great news! Now everyone could be on the most up to date baseband firmware and still use any GSM carrier they wanted, right? Not necessarily!
Before the software unlock was released, most users (including myself) had been using Proxy Sims to use the iPhone on networks other than AT&T (T-Mobile for me.) A Proxy Sim (for those not wanting to read up) is simply a small paper thin chip that sits between your sim card and the tray that tricks the phone into thinking you are using an authentic sim card belonging to the carrier to which the phone is locked.
The majority of these Proxy Sims (such as the Gevey 3g mentioned in the earlier link) were built to work on the 2.11.07 baseband firmware. So, if you updated to the new baseband firmware, your Proxy Sim would no longer work and you’d be stuck with a much more expensive version of the iPod Touch.