[cisco-voip] Emergency Responder Issue with Inbound Calls?

[Dark Fiber]

I have my ER up and working partially it would seem.  I have ERL's
defined, and phones placed in them.  I have my ELINS and such working
so that when a call goes out the CPN is changed to one of the DID's
and I do reach the correct PSAP.

So far so good.

However, I tested a return call and I have an issue.

Can't seem to reach the user who called 911.  I can see the call hit
the gateway so I know its not a telco issue regarding my DIDs.

Kinda thinking it might be a issue with significant digits?  Sig
digits on these PRI's are all 4 since they handle our normal DID's as
well for office extensions.

Any thoughts on how to best confirm that sig digits are the issue?
Any insight as to some of the ramifications of adjusting the sig
digits on the gateway and what else would have to be adjusted?