There's a template built into the 5000 and it went pretty well EXCEPT it was using the wrong peer address sometimes. If Bandwidth sent call through a different server anywhere at their end it broke down. A known issue, but documentation is hard to find. Got the below from tech support, now all is well:
The "Use peer address in FROM header" is not what we should be using for this.
Engineering was made aware of this issue a while back - and, they re-engineered the SIP TG's configuration field for "Alternate IP / FQDN List" so that you can create a new entry within that table, set it as FQDN - then type "default" - all lower case and without the brackets into the new Alternate IP / FQDN List - which, will then allow any traffic from Bandwidth.com to properly operate - regardless of which IP Addressing the traffic is routing.