What are some alternatives?
When comparing Google Voice and Viber, you can also consider the following products
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
UberConference - UberConference provides a rich visual interface for conference calls. Simple, visual, and free to use, it's audio conferencing done right.
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
8x8 - 8x8's VoIP business phone systems deliver affordable, cloud-based voice, video, messaging, and call center solutions, helping you serve customers anytime, anywhere.
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.