I got Grandstream HT812/814 hoping to set it up to use as an intercom or public announcement with my phone system. The ATA is registered and I'm trying to create one way audio so that you can just call it and have a speech path through the AMP that has TEL input. Is there any other setting in PCPro or on the ATA itself I need to do? Right now it just goes off-hook and you can not call it i.e have speech path.