24/7 Mobile Solutions recently announced its latest product, SIMable, a new solution to unlocking your handset. This is, in fact, a thin chip that can be attached to your SIM card. When a SIM card with a SIMable chip attached to it is inserted into your handset, the phone is unlocked, meaning that you can use it on different networks.
This product doesn't meddle with your integrated phone software, nor does it do anything that might render your warranty void. It’s a simple hardware add-on that overrides your phone’s SIM Lock, so it doesn’t unlock the phone – just the SIM. Once you remove it from your phone, your phone reverts to its original state and you can use it on the network you bought it from.
You can read more specs here.