Select the channels whose members are allowed to submit call requests to you. For that, use the check boxes in the This channel and Dynamic channels columns of the channel table. If This channel is selected for a channel, its direct members can submit call requests. If Dynamic channels is selected, members of the channel's dynamic subchannels can submit call requests.
Select the Show callback requests from deleted channels option if necessary.
To respond to call requests made by people from the approved channels, use the Call Queue plugin.