I see Nlets referenced in the IEPD materials … is the Nlets network path proposed as part of the standard?

NO, there is no network path proposed as a standard in the candidate ANS.  Multiple exchange delivery options are available.  The materials simply document that Nlets was the selected transport mechanism for the pilot between Vector Security (the CSAA participant) and the two Virginia PSAPs, and for them, offered the best solution.  Originally the pilot started with direct interchanges between Vector Security and each of the two Virginia PSAPs via the Internet.  The development team realized that there were many security issues that would need to be addressed as the pilot expanded to include additional alarm companies and PSAPs.  The pilot did not have the luxury of a centralized registration server to validate senders and receivers.  Nlets was contacted by the development team and offered their network as a viable alternative which provides that central security focal point to achieve proof of concept.  Effectively, each alarm company has a single VPN tunnel established to Nlets without the need for hundreds or even thousands of alternate connections.  The IP address contained in each message allows Nlets to route the traffic to the appropriate PSAP via a dedicate link to each state, in this case the State of Virginia.  Network engineers at the Virginia State Police and Nlets established the necessary Nat rules to achieve transparent end-to-end communications between Vector Security and the Virginia PSAPs.  Readers should not confuse these alarm exchanges sent via Nlets with the routine Nlets traffic received on Teletype/State terminals.  While the path is similar, all transmissions from the alarm companies are routed to either a middleware server ahead of the CAD system or the CAD system itself.