Try forwarding your Freedigits number in the Dashboard page to
xxxxxx@voxalot.com
This should work. If it does not, maybe you should contact FreeDigits support.
I did have a problem with my Freedigits account when I first set it up. Incoming calls did not come through correctly, even when the account was registered on an ATA.
They did fix the problem after several weeks, and they followed up by a phone call at 3:00AM to verify. Hmmm.....