I am considering ordering HughesNet Voice but after trying my phone on an Ooma device, I’m not sure if it will work.
On the bottom of Voice’s sales page it states the equipment has to be returned within 30 days to avoid an equipment charge. I read the, HughesNet Voice Service Addendum to Residential Subscriber Agreement but it says nothing about not being locked into the 24 month contract.
Is there any cancellation window of time to cancel Voice and void the 24 month contract?
No, there is no cancellation window in which to cancel without the commitment or being required to pay an Early Termination Fee . Like the HughesNet service itself, the 24 month commitment is active the second the service goes live.
Also, please keep in mind that, although 3rd party Voice services often don't work with HughesNet, HughesNet's own Voice service is specifically designed to do so.
Edit: I should add that it's actually 45 days from the date of cancellation that you have to return the ATA. If they don't get it back within this amount of time they will charge a $75 un-returned equipment fee. You can see the legal particulars for the Voice Service, including the info I have given, here.