CutYourSIM is a well known remote unlocking service that has made a permanent unlock for all iPhone’s including the 4S that are locked on AT&T.
The CutYourSIM unlock will be done remotely through iTunes and will be a permanent solution for your iPhone. You can now update your iPhone to the newest firmware version without worrying about waiting unlock to be released.
The CutYourSIM service requires you to provide your iPhone’s IMEI number followed by purchasing there service. They will then permanently unlock your iPhone remotely. The process takes around 5-20 business days and works on all iPhone models.
The CutYourSIM unlock will cost you $185 and can be purchased here.