It lets you start a private Slack Call or launch a conference call in a channel that anyone can join with a click. And in keeping with Slack’s lighthearted style, once you’re chatting, you can send visual emoji reactions that appear overlaid on your profile picture to others on the call.

Slack confirms to me that the feature is currently rolled out to less than 50% of users. Team admins can check if it’s available to them and turn it on here.

Slack already offered integrations with voice calling apps like Skype, Google Hangouts, Zoom, and Bluejeans, but those required a separate installation and were quite clunky by comparison. Slack Calls just need to be enabled by your team’s admin, are super easy to use, and blend naturally into the Slack experience.
Slack says that video chat is also in the works, which it first announced last year after acquiring Screenhero. But now it’s on the official roadmap, though the company plans to get voice chat rolled out on all devices first.

How Slack Calls Work

First, you’ll have to download the latest version of Slack for desktop and make sure your team’s admin has enabled Calls in the Team Settings. You’ll then see a phone icon at the top of your one-on-one threads and channels.

Tap the phone icon and a Slack Call pings your private message partner with a pop-up window beckoning them to answer. Once you’re in a call, you can change your microphone settings (unlike Skype which makes you set that before a call) or add more people to the call.
Slack didn’t bring all its emoji along, but the Smiley-face button reveals a few you can tap to silently let Call partners know how you feel. The emoji pop up on top of your profile picture in the corner. It’s like a visual nod over the phone. They say something you agree with, and you hit the heart or smile so they know without interrupting them.
On channels, hitting the Call button prompts you name the call and then wait for others to join.
Your channel partners will see a button to join in the text thread so anyone available can quickly jump on.

And just for giggles, tapping the main avatar in your call causes it to pulse satisfyingly.
When I spoke to Slack’s VP Of Product April Underwood yesterday, she told me the use case for Slack Calls was that “If I’m DMing someone in Slack and we want to switch to have a quick voice conversation, it addresses that problem.”
Apparently voice calling was one of the most heavily requested options from Slack’s 2.3 million daily active users and 570,000 paid subscribers. Yesterday’s customer conference and the release of hotly anticipated features could help boost Slack’s momentum as it reportedly looks to raise at least another $150 million.

By becoming more of a full-service communication suite rather than just a text chat tool, Slack might be able to convince more companies to pay for it — especially because businesses might already be spending money to have voice chat. Slack Calls could threaten Skype and Google Hangouts, which increasingly feel inconvenient.