Peering is not required to resolve this issue. The problem as I read it, is that sipgate is not setup as a registered provider within VoXaLot.
As occamsrazor suggests, try setting Sip Register set to "YES" on the provider details page and make sure the status says "Registered".
Peering only comes into play with something like
SIP Broker.
The other possibility is that your VoXaLot inbounds are not working. Try dialing one of the
PSTN Access Numbers and at the voice prompt, dial:
*010xxxxxx (where xxxxxx is your VoXaLot number).