I was thinking of using the CSS/Device Pools as a starting point to get the "main number" sent to the PSAP since I have found many of the DN in the system do not have an External Phone Number Mask set up on the endpoints and we have a lot of non-DID numbers. That way I could cover groups of phones rather than having to drill down to each individual phone right away. Thankfully most of our locations are small and most every phone has an instance of the "main number" DN.
You need to be careful with presenting main number to PSAP as that will prevent callbacks from reaching the actual phone that dialed 911 in case the call disconnects. This is where application such as CER can be helpful as it can route callbacks to non-DIDs, etc.
My testing has shown without having the digit manipulation on the 911 route pattern Caller ID only gets the 4 digit extension (plus the #1 for the US) and not the correct 10 digit phone number. Is there a way to correct this without hitting each device and adding the correct outgoing number to the DN instance?
Yes, it all comes down to how your CUCM and GW are configured. Is the route pattern configured not to use external phone number mask and the "calling party transformation" was set with the 10 digit number? How about the Route List/Route group, is external mask disabled there too?
Are there any transformations taking place on the GW?
What does the debug show (debug ccsip messages)?
Another fun fact I found is that we have locations that a local POTs line is forwarded to a DID that is part of our CUCM. Any suggestions on how to tackle 911 for these?
Not sure I follow this, you have POTS lines (FXO ports) used by CUCM or inbound or outbound or both? Are there 911 patterns pointing to it, if not how is this related to 911?
