Sony can be unlocked by a code. After unlock you can use it worldwide. It is the safest and fastest method. This unlocking service is independent of the network. It is 100% secured. If the device asks for an unlock code it can be unlocked easily.
Unlocking instructions for Sony
How to enter an unlock code on a Sony?
1. Turn on Sony with a different network sim card.
2. Enter the unlock code provided by cellcute.com.
Now your Sony is unlocked.