Skype is an instant messaging and VOIP (Voice Over Internet Protocol) client to communicate with people in a distant place.

Viber Free Messenger and Phone Calls.

Yahoo! Messenger (sometimes abbreviated Y!M) is an advertisement-supported instant messaging client and associated protocol provided by Yahoo.

ooVoo is a video chat and an instant messaging client.

SightCall remote support software enables live video streaming and remote access on mobile devices and desktops for customer service and tech support.

WhatsApp Messenger is an instant messaging platform owned by Facebook.

Jitsi (formerly SIP Communicator) is a free and open source multiplatform voice (VoIP), videoconferencing and instant messaging application.

Fring connects with Skype, MSN Messenger, ICQ and Google Talk from your iPhone.

Google Duo is a video chat mobile app available on the Android and iOS operating systems.