We use Hangouts to facilitate quick and easy chats via text, audio, and video, with no additional configuration to speak of over and above a little bit of training for novice users. It uses their existing Google accounts and doesn't require much else, and even works on ChromeOS devices. Outstanding, perhaps even superior, mobile apps complete the package. There are products that perform better, but Hangouts has ease of use and supports at minimum 10 users at a time with little scheduling or planning overhead. It even integrates with Google Calendar!