You can use your Verizon Galaxy S3 as global phone, without having to wait for the software update that VZW promised it will release soon. Thanks to XDA member lair12, you now have a workaround that lets you unlock Galaxy S3 on Verizon Wireless and makes your phone a global phone. This is especially useful for those who are travelling abroad and want to take their phone with them.
The guide is pretty complex, but its worth the effort and appears to be working for many users confirming the claims of the developer. You will need to root SGS3 first, and then install some apps from the Google Play Store.
How to Use Verizon CDMA Galaxy S3 as GSM / Global Phone
This guide is divided in 4 parts.
Part 1: Rooting and installing required apps
Part 2: Convert LTE to GSM
Part 3: Return back to LTE from GSM
Part 4: What to do if it fails.
All these 4 parts are explained on official thread over at XDA Developers Forums. Follow the guide and have fun!
For those of you who find it difficult, you can wait for official software update from Verizon Wireless that will eventually unlock Samsung Galaxy S3, allowing you to use it as a world phone.
More info at: XDA