Ok, I got a reply.
Must have a Verizon PRL flashed to the phone.
This means, do not use the update profile & PRL option in the ROM or it may wipe out the PRL. He didn't specify which JB modem to use however.
Edit: You will need your MSL to update the prl on the phone and unless you already have it, I understand its not easy to retrieve on a non-Sprint phone if that is what you've got.