You can use the phone connection worldwide (“nomadic use”). That’s why you can call like you’re at home when you’re on holidays or on business trips abroad. You only need an internet connection at your places and a connected VoIP compatible device like a smartphone, an IP phone or a softphone.
You can activate many devices at the same time. They ring simultaneously without any extra fees for forwarding. Now it is possible to be available via one number at more than one place at the same time.