Video calling can be done with a number of (free) apps. Here are some of the most common:
Skype is the most popular app. It is available to both mobile devices and computers, and the “find friends” option works easily. There is no requirement to use your phone number to identify you, which provides greater anonymity. It also offers group calls.
FaceTime only offers basic features and is limited to Apple customers. All Apple users have access to it since it comes preloaded on their devices.
Facebook Messenger gives all Facebook users access to texting, group calls, emojis, sharing files and video calling. It is available on all devices and computer platforms that support Facebook. The downside is the limited encryption and configuration options.
Google Duo is available to everyone—iOS as well as Android. It is more powerful than Google’s own Hangout, although it cannot send files; Duo is designed strictly for video calls.
What’s App is simpler and can be used on any mobile device. A bonus with this app is the ability to tag a phone number as a solicitor, scam, sales call, etc., tipping you off to avoid answering certain calls.