Here is the more details of the Gevey Turbo Sim, and it is abour $19.99 now: http://www.totobay.com/
If you have purchased an iPhone 4 that signed up with Apple's exclusive carrier in the US, AT&T, That means, your iPhone 4 identifies itself to AT&T networking, you can use your iPhone 4 only with AT&T sim card. But, if you'd prefer to use T-Mobile as your cellular provider, rather than AT&T somtimes, How you can "Unlock" your iPhone 4, allowing it to use a SIM Card from any provider.
But, what is Gevey Sim, An interposer is an electrical interface that directs the connection from one socket to another. The purpose of a sim interposer in this case is tore-route a connectionto a different connection which can then unlock the iphone 4. Gevey Sim Interposer is an integrated circuit which contains the unlock exploit using emergency number dialing . The video below can explain the integration in a better way .
Here's what to do to unlock with Gevey Sim:
* Turn off the iPhone 4;
* Place the adapter into the holder, on top put your micro-SIM;
* Get the design insert in the iPhone, turn;
* The status bar displays "No Signal". Wait until its place appears the signal strength indicator;
* When this happens, call the emergency 112 call, and resets after 2 seconds;
* You go to Settings and turn Airplane Mode, and then turn it off;
* iPhone displays the message "Error SIM-card" and then "SIM-card inserted.”Click OK, and then again turn on Airplane Mode and turn it off again;
* "Error SIM-card reappears, but after a couple of seconds it will disappear and you will be able to use communication services. All this will need to do every time you reboot the phone.