Android and iOS beta users of Slack are getting access to calls using their devices. Calls, the Slack term for this feature, has been available for desktop users who activated the feature since last month. Now, to use it on your mobile app, you just need to open an individual or group direct message and then tap on the small arrow icon to show the menu. Near the end of the menu there’s a feature that says “Call (user).” The feature has been made available since late last week.
Source: The Next Web