CER problem - Call delivers correct ELIN but goes to National instead of local

[Keith Abbott]

Good Day,
Im hoping someone can help me with a CER issue Ive encountered. I dont have too much experience with it and am not sure if this is an issue on our side or something we have to work out with the carrier.

We have a remote site with an old odd-man-out phone system, which we are in the process of changing over to our current Cisco Phone system (CM 11.5).

CER has been in place and working on the Cisco system for some years, so all of the 912 and 913 foundation stuff is configured and working correctly.

I configured CER and the necessary route pattern. 1<10-dig-ELIN>.911 - route partition 'System CER' (on our system) - GW/RL - Emergency - which points to SLRG - Which verified points to correct GW.

I configured the conventional ERL and added the ALI details, and had the site manager verify the address and phone number.
I set up phone tracking and verified the site's cisco phones are appearing.

Ive read through https://community.cisco.com/t5/collaboration-voice-and-video/cisco-emergency-responder-cer-explained/ta-p/3138289

The issue is that when a 911 call is made from the old - non-cisco system, (which I believe is delivered via a local POTS), the call successfully goes to the local PSAP, and has the correct ALI: but the call from the cisco phone, while delivering exactly the same ELIN (Per the 911 operator, the CER record, and the CDR record), went to National and did not display an address. The Cisco call was delivered to the expected, remote, gateway.

My belief, perhaps erroneous, was that the PSAP did a lookup based on ELIN, and if the ELIN was the same, the rest would fall into place, and that was one of the jobs/advantages, of CER was to make 911 calls exiting a centralized site, look like they exited from the local site, therefore get local PSAP and pull the correct addr.
So my questions are,
1. is this something we need to work with the carrier on, or is it probably something on our end?
2. If the latter, where should I look?
3. Are my basic understandings correct:
a. If we deliver the correct ELIN the rest should fall into place
b. CER should make the 911 call look like it came from the

[Jonathan Schulenberg · Accepted solution]

CER is far less magical than that. All CER can do is figure out the appropriate ELIN for the calling party’s location and overwrite the ANI before handing the call back to CUCM. It has no direct line of communication to the PSAP (at least not without RedSky or Intrado, but that’s a whole other ball game).
The ALI record for an ELIN is either manually updated by the carrier (SP-ALI) or by the customer through a portal (PS-ALI).
It matters where you hand the call off to the carrier because the Selective Service Routers that connect to a PSAP are not part of the normal PSTN; POTS and ISDN circuits can only hand calls off to the local SSR connected to the CO switch landing that circuit, and maybe a few others in a metro area. Centralized SIP trunks support centralized 911 calls only if you have ordered every remote site as a virtual branch office location. It’s not unheard of for a centralized SIP trunk to lack 911 service for rural/remote addresses owned by a small LEC.
You will need to get your centralized carrier involved, route the call out the local circuit in that branch, or look at RedSky/Intrado (again, much larger topic there).

[Keith Abbott]

Hi Jonathan,

Thanks for the response. I believe you've hit the answer. In the case of the existing phone system, it would be routing the call out a local POTS to a small carrier - and it is a different carrier than is the centralized egress point.

We are reaching out to our carrier and I'll update the ticket when I know more

thx