Even though these are free apps, be careful!

Most Secure: WhatsApp

WhatsApp

Free voice and video calls.

Group calling available (up to 32 people).

Rendering of a globe sitting on a smartphone.

mrhighsky/Getty

Frequent use could cause data overage.

Encryption only if both parties have the right version of app.

The app also supports group calls.

WhatsApp collage showing various calling states.

WhatsApp

WhatsApp includes end-to-end encryption that applies to all messages and calls using the app.

However, if youre chatting with someone who has an older version, none of your communications are encrypted.

There are also web and desktop versions, meaning you canuse WhatsApp on your system.

An active FaceTime video call

Apple

Communications protected by end-to-end encryption.

Fun extras like background effects, reactions, and SharePlay support.

Android users can only join calls, not start them.

Google Voice screens in various formats.

Google

Older devices only support video, not voice, calls.

FaceTimeis a free voice and video call app for iPhone, iPad, iPod touch, and Mac.

You cancall people over Wi-Fi or using mobile dataaround the world, except for a handful of countries.

Depiction of a Skype call with a woman on the receiving screen.

Skype

To set up an account, you need an Apple ID/Apple Account.

To contact friends, you need the phone number or email associated with their Apple Account.

Can record incoming calls.

Screenshots showing how Viber video calls work.

Can only make outgoing calls from the U.S.

Free calls available only between the U.S. and Canada.

Not free to call landlines, only other Google Voice numbers.

Google Voice is a VoIP service thats mostly free.

In addition to Android and iOS apps, you could also use Google Voice in a desktop web app.

If youre in the U.S., most calls to people in the U.S. and Canada are free.

Rates for calls to other parts of the world vary.Google Voice calling ratesare listed on their website.

Best For Group Calls: Skype

Skype

Free calls to Skype users.

Send video or voice message if call missed.

Risk of data overage.

Good VoIP App: Viber

Free calls to other Viber users.

End-to-end encryption for 1-on-1 chats and calls.

Group calls are not encrypted.

Viber has mobile and desktop apps.

Examples include Skype, WhatsApp, and Google Voice.

The price of international calls can depend on your cellular carrier.

Other plans may offer unlimited texting.