Here’s something Android users might be feeling envious over iOS users: the ability to start video calls right from Phone and Messages app. Google users, specifically those who have Pixel, Nexus, and Android One users, will soon be able to video call right from Phone, Contacts, and Android Messages apps.
To make this possible, Google is using its Duo video calling service and the ViLTE standard. The latter is an extension of the current VoLTE standard, which focuses on better video call quality over an LTE network. By default, video calls will be routed through ViLTE. That is if your carrier supports that standard. If they don’t, Google will route it through Duo. This means, you’ll need to have Duo installed and activated on your device. You also need to have the latest versions of the aforementioned apps. Later this year, Google also plans to give you the option to upgrade a voice call to a video call.
Source: Android Authority