Though I don't know for sure that this will help, it certainly won't hurt to try.
1. Unplug your Voice ATA.
2. Unplug the HughesNet modem.
3. After about a minute, plug the HughesNet modem back in.
4. After waiting a minute or so, which will give the modem time to be fully back up and ready, plug the ATA back in.
5. After again waiting for a minute or two in order to give the ATA time to be back up and fully ready, give it a try.
Again, it may help, though it may not, but it won't hurt to try.
If it doesn't, I'd either call 866-347-3292 for customer service, or wait to see what the reps here have to say. They're on Monday thru Friday from approximately 9AM to 6PM EST. If it doesn't help and you'd rather wait to see what the reps here have to say, make sure to reply that it didn't work so that they know to reply to help.