Hello Rob! I ran some tests with your ATA box and everything came out great on HughesNet's end. What you can try is hooking up a different phone to the ATA box, and testing your calls to see if the calls stay steady or not. This can rule out if there's an issue with the phone itself or not.
Rob, you can disregard my private message, it appears my case has been placed under review by Voice Support today. They should contact you within a few days or so.