Voice2Go

We recently had trouble with our Xfinity voice that has mostly been resolved. We have two phone numbers, one is our main number, the other is for a fax machine. Until our troubles, our main number was the number that would be used for Voice2Go. Ever since we had the problems, Voice2Go defaults to my fax number. That does me no good as no one calls me on that number. Does anyone know how I can switch the Voice2Go back to my main number? There doesn't seem to be an option in "Settings" to do that.