I finally downloaded the Whatsapp app. I have a relative traveling out of the country for a few months who I need to keep in contact with. I have a few questions on this app. It asked to sync into both our CONTACTS, which we both agreed to. However, once my relative travels abroad and has to replace her current sim with a local sim for the country they are visiting. 1. Obviously I won't be able to text them through Whatsapp until they first text me, because of their new local number, am I correct? 2. Do they then have to allow the Whatspp app to allow and sync to their contacts with this new number? 3. I see that the Whatsapp app has a calling feature. Does this app act similar to VIBER and are international calls "free" if both parties have the 'Whatsapp' app? Thank you!