Yes, you can actually make free calls over the internet. The apps I will mention come in two types: some only work if the other person has the same app, while others let you call landlines and almost any other number.

Anyway, it's a free call and these apps are the best for that. I keep a few of my favorites on my phone for when I don't have a good signal, like in certain hotels or airports.

Google Meet is an app-to-app calling service that works on desktop and mobile platforms. Video meetings are encrypted, it supports both video and audio calling, and you can form massive group calls with up to 100 people.

What I like about this app is that it displays real-time subtitles while the other person is speaking.