You need to take advantage of the Customer Support section on the Amtelco website in order to find this information because there is nothing publicly available for users. I've also searched for user guides and troubleshooting documents, but nothing could be found. Access the link I've posted below to reach the Customer Support page. If you are their customer, then support is free and they should answer your inquiries.
Customer support page: http://www.amtelco.com/customer-support