You need to be physically in the other country to use it and have a valid credit card and billing address for that other country

CHANGING APPLE ID/EDIT ACCOUNT INFORMATION/CHANGE ITUNES COUNTRY

Tap Settings / iTunes & App Stores, then tap the Apple ID signed in. Sign out of the current Apple ID account and then sign in with another account or create a new Apple ID http://support.apple.com/kb/HT2731?viewlocale=en_US

Go to settings/facetime and tap the ID there and log out and log in with new ID.

Go to settings/messages and turn off imessages wait 30 seconds and turn it back on, go to “receive messages  at” tap on the ID there, sign out and sign in with new ID.

Go to settings/icloud and delete the account and when prompted select “keep information on your device” then turn it back on with the new ID.

To edit account information tap Settings / iTunes & App Stores / Apple ID: / View Apple ID

To change your iTunes Store country, sign in to the account for the iTunes Store region you would like to use, tap Settings/iTunes & App Store/Apple ID/View Apple ID/Country/Region

Read this article for information http://support.apple.com/kb/HT1311