Unfortunately, with it being after hours on a Friday evening, the soonest you'll likely hear from a rep on here will be Monday.
With this said, there is something you can try that may help...
1. Unplug the ATA (Voice unit).
2. Unplug your 3rd party router (if you have one).
3. Unplug the HughesNet modem at the wall outlet or power pack, NOT at the back of the modem.
4. Check to make sure your cables are well connected.
5. Wait for at least a minute after unplugging the HughesNet modem, then plug the modem back in.
6. Wait for about five minutes so that the HughesNet modem is fully back up and running, then plug in the router (if you have one).
7. Wait for the router to be fully back up and running (usually a minute or two), then plug in the ATA.
8. I don't have an ATA, so I don't know if it takes time to be fully powered up, but if it does, wait that time, then try your phone again and see if the problem is resolved.
Though there are no guarantees, hopefully this will help. If not, please be sure to reply, though again, it's likely that you won't hear anything from a rep on here until at least Monday. Still, others may have an idea of what to try. If you'd rather not wait, or more likely simply can't wait, you can call HughesNet Customer Service at 866-347-3292 if you have other phone service available to you. Customer Service via phone is normally the only HughesNet rep help available during the weekends.