If those contacts are Google Hangout users, you can call them entirely for free.
You can call landlines and mobiles from Hangouts, too.
When a recipient clicks the link, the room will open in their browser (this works on mobile, too).
You can choose to either have a voice or video call, and you can also share your screen.
The resolution of the videos is not quite like at the premium sites, but it's pretty alright.It was so popular, in fact, that “Skyping” became a verb.But with so many complaints of low quality calls, too many crashes, and a general distrust of Microsoft, for many, Skype lost its appeal, despite its recent overhauls.It’s basically like Whats App, but also allows calls to landlines and web-based calls to non-users. Also, includes games, public chats, and calls to mobiles and landlines.If you make a lot of international calls, Viber is a massively popular ad-free option, available on most platforms including the desktop (on Mac and Linux, too).