Well try to point to any of these and see if you have results:
1. 123456@voxalot.com
2. 123456@xx.voxalot.com (xx is us, au, or eu depending on which cluster you are using, see main page when logged into VoXalot Account on the web)
3. *010123456@sipbroker.com
Naturally replace 123456 with your VoXalot Number. If all that fails, it's possible this provider is having issues with forwarding....
To check that their problem is not VoXalot Specific, get yourself an FWD account and forward there. If that works, you can then have FWD forward to VoXalot (I can confirm FWD to VoXalot does work)
For the time being VoXalot does not have a Help Ticket system (although word is that one is in the plans)