To get the unlock code you need for your Xperia Arc you should first try asking your network service provider. If you have been a customer of theirs for a while they may offer you the unlock code for free,
Sony Ericsson Xperia Arc
Unlock Codes for Sony Ericsson Xperia Arc, a detailed set of instructions to be able to unlock your transportable. Numerous tips and tricks on how to get your cell phone unlocked with 24/7 expert support. You can trust us, 10,000 Facebook fans do.
The Sony Ericsson Xperia Arc (LT15) is part of the popular Sony Ericsson Xperia series of smartphones. The LT15 runs on the Android platform, and was released in 2011. It has a uniquely curved shape, and an extremely bright and vivid screen. It also features excellent high definition video capture capabilities in any light, and the ability to display videos on an HD television.