That's so odd.. I thought it was 10 times harder to get Inbound set up than outbound with V1VoIP. We were able to get everything working, but there were only 2 issues we had with V1Voip on initial setup:
In our switch that's using V1Voip, I have 3 SIP servers allowed in the Access Control list. This server is working fine, but per the documentation at the time we set it up, those SIP servers you need to add to ACCESS CONTROLS > DOMAINS > ALLOW were:
allow 207.239.159.171/32 sip1.v1viop.com
allow 173.246.36.196/32 sip2.v1voip.com
allow 207.239.151.40/32 sip3.v1voip.com
The other issue was that by default, V1VoIP was set up for a 10 digit vs. 11 digit dial plan. V1Voip's portal has changed recently, but you can still find their 10 digit or 11 digit SIP Type field under DIDS > Forwarding.