Between is available anywhere in the world, as long as you can connect to a 3G or Wi-Fi network.
You can use the service for free over Wi-Fi, but you may be charged for data roaming if on a 3G network. Please check with your carrier before using Between on data networks overseas.
Calling your partner will lead to voice call on your device.
Getting a new phone or changing SIM card will not affect your data. Please download Between again on your new phone and log in with your Between ID to resume where you left off.