Google Talk is the instant messaging apps that's been available to all Android smartphones almost since day one.
It works between Android smartphones, tablets and desktop-based browsers.
Facebook is pushing hard to be the mobile messaging platform of choice for many users.
It fact, it recently updated its Facebook Messenger app to include a unique new feature called Chat Heads.
In order to chat between an i Phone and a Galaxy S 4, however, both devices need to use Chat On. It lets i Phone, i Pad and i Pod Touch users send messages back and forth through the devices' data connection.