You can make noiseless calls using Krisp with Slack.
After you download and install Krisp, configuring with Slack is super simple.
1. Start a call with Slack
Start a call in Slack.
2. Select Krisp as a microphone & speaker
Open audio settings while in the call and select Krisp microphone and speaker in the audio settings.
3. Mute the Noise
Choose the correct microphone in Krisp menu. Make sure that Mute Noise toggle is turned on in Krisp UI.
The "in use" indicator will be On if there is an ongoing call.
Here's a quick video tutorial to help you along the way
Krisp with Slack on Mac
Krisp with Slack on Windows