Tech support got back to me with this: "As for direct SIP scanning our ATA uses a non-standard SIP port (usually 5078/5079) which helps 'hide' the device from SIP scanning of normal SIP ports (5060). However, this can also usually be done within the BYOD itself. By adjusting the port on which it connects you can also have it use non-standard SIP ports like 5078/5079." So I should be OK now.