code: public void dndOn() throws WorkspaceApiException {
          try {
              ApiSuccessResponse response = this.voiceApi.setDNDOn(null);
              throwIfNotOk("dndOn", response);
          } catch (ApiException e) {
              throw new WorkspaceApiException("dndOn failed.", e);
          }
      }
docs: Set the current agent's state to Do Not Disturb on the voice channel.