Tox is an open source secure alternative to the likes of Skype. To install it, you need to install the core package and one of the available GUIs. You can compare some of the available clients here but personally I like
qtox. The below will pull in the required dependencies.
sudo pacman -Sy qtox
If you want the latest Git version, you can install
qtox-git from the AUR.
yaourt -S qtox-git
Make sure you run that as a regular user – not root. This pulls in the core package from the ABS repository also.
To add a contact, you will need their Tox ID – which looks like this: