Join Date:Joined: Feb 2012
I used it, 3 years ago... You only require a phone with a "sim menu", (the one with your carrier options... And a case big enough to be able to close it with this sim that is a little bit thicker.
The one I tested made disappear your carrier "sim menu", and replaced it with a custom menu that allowed to change the sim... Even allowed to schedule the changes...
The bad thing is the time it takes to obtain signal after making the change ( the same time it takes when you turn on the phone), and that you have to cut your SIMs to be able to insert them...
Now I sow one that did'n require to cut the Sim, but I think that's too big for lots of phones.