You can use a DID number from any DID provider like for example
Callcentric - VoIP Internet phone service,
DID Provider | DID Numbers | Wholesale DIDs | DIDWW,
FREE IP Calling with IPKall
forwarded to your Voxalot Account.
You have to verify the DID number in your Google Voice Account before GV allows you to forward to it.
The IPKall DID must get a minimum of 1 call every 4 weeks to stay active.