1. If you enable listener call-in, your listeners can request to call in. When listeners are calling in, you can click the Invite button on the calling message, or click the microphone icon under "Call In" section to invite them. 

You can also click the profile photo of the listener-->click the Invite as Speaker button to invite them to join.

2. After connecting with your listeners, you can click their profile photo-->click the Disconnect button to hang up the call, or click the Mute button to mute them.

3. If you disable listener call in, your listeners will receive a message saying “Call-in is turned off right now" when they try to call.