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• ability to group instant messages into group of members or via topics (or both)
• mobile clients so you can respond on your phone
• ability to search messages
• messages are seamlessly synced to all devices, mobile and desktop
• integrates with other third party services (Dropbox, Twitter, etc)

Group chat services

The TTF will be evaluating several of these group chat services to see if these could be used by At-Large

• Slack (http://www.slack.com) - The At-Large Social Media Working Group used Slack https://icann-at-large.slack.com/ during the ICANN 50th London meeting to coordinate content for sharing during the At-Large Summit II. 
• HipChat (https://www.hipchat.com/)
• Hall (https://hall.com/) - Note that Hall was acquired/merged with HipChat
• Rocket.chat - The TTF has had a demo of Rocket.chat by James Gannon from the NCUC at the ICANN56 Helsinki meeting and a followup demo on the 2016-09-19 At-Large Technology Taskforce Call
• Skype

What is Slack

Here's a YouTube video "What is Slack?" from the makers of Slack which gives an overview of the features of Slack

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