Enable NAT on provider's side?

[TBhimdi]

I currently have Voxalot registered to Vitelity and setup for incoming & outgoing calls. I also have symmetric NAT disabled in Voxalot settings so that I'm sure that no voice traffic goes through Voxalot's server. But what I'm not sure of is the setting in Vitelity's panel.

Should I disable or enable NAT in my Vitelity panel? Voxalot isn't behind a NAT, but I am, so I don't know which one should be the "best" selection. Currently Vitelity has NAT enabled and things are working fine with my Vitelity DID, incoming and outgoing. Btw, I had to set my DID routing to "SIP Device", setting it as SIP PBX breaks incoming calls via Voxalot (outgoing still work fine, Voxalot is registered and everything).

Also, Les.net has the same NAT option, but it also has an option to enable or disable Re-Invite. I'm assuming re-invites need to be enabled? I haven't yet used Les.net with Voxalot, so just curious right now.