While the whole unlocking and jailbreaking community was celebrating the successful unlock / jailbreak of iOS 5 on devices that had the A4 chip, the ones with the A5 chip had to wait. In fact, even now, there is no public release of the jailbreak / unlock for iOS 5.1.
We had all the jailbreaking / unlocking techies telling everyone not to upgrade to iOS 5.1 because there are a lot of complications involved in it. The baseband is different, the SHSH Blobs will no longer be signed and a lot of other issues come along with the update.
Of course, one would not want to wait long. R-SIM 3 seems to solve this.
One video here shows how to unlock iPhone 4S on iOS 5.1 with R-SIM 3. It’s a simple, one-step process and all you need to do is insert the R-SIM 3 along with the SIM you use. The solution has been shown to work on AT&T and quite a lot of users have reported (on other websites) that R-SIM 3 also works for Verizon and Sprint.
There were complications with both R-SIM and R-SIM 2 but those seem to have been removed totally from the current version of R-SIM.
While developers are still working hard to produce a working unlock for iPhone 4S on iOS 5.1, the hardware side of it seems to have gotten a bit ahead faster. R-SIM 3 works supports the F300 chip which reduces battery consumption and enhances the call quality.
The other bands that R-SIM 3 can unlock are:
iOS 5.0 and iOS 5.0.1 on the following basebands: 1.0.11, 1.0.13 and 1.0.14.
A final note: this is a completely legal way to unlock your iPhone 5 on iOS 5.1.
See The Video Of R-Sim III 3rd Generation Unlock IOS 5.1