When working with E911 just be sure to test your configurations to ensure the desired outcome. If you’re not using a routing service , CER is going to just transform calling party numbers so you can monitor how it works by changing the destination of an ERL.
@vasu_hanu66
1. I want to know how to track the phones. I have enabled snmp on CER and CUCM. but not enabled snmp on our switches. Instead of Switches , I want to add super-net of the respective locations to add those phones to respective ERL's. Does it work only by adding IP Segments and not included in switches to CER?
You can use the subnet based layer 3 tracking to specify a network and assign it an ERL. Multiple networks can have the same ERL. This provides you only with a relative location when taking this approach, but more specific than the default system location. NENA Guidelines for ERL zoning usually recommend a maximum size to the ERL in square footage to minimize the amount of searching emergency responders need to do, but you may not be able to be too specific without changing infrastructure- or you may not need to be in the case of an office suite or smaller location.
2. Need clarification on ALI details. What ever the details update in ALI of CER , does it replicate with PASP? or database maintain by the carrier it shows. Also, do we need to get in touch with carrier to show the ALI information on our CER?
If you use a V911 service, then it can sync if you update the ALI details after validating them . Otherwise you either can use the NENA PSALI formatting tools to export your data and send to the provider / use their tools , or you update it yourself. Consult your carrier as to which services they offer, and what flexibility they will allow you to make changes .
3. Also want to know what does default ERL do? As I understood, if phone not part of ip segment or configured swtichport and dialed 911, uses default ERL's.. what it couple of numbers of dialed 911 and not matches the existing erls then uses the default ERL's. But default erls has only ALI info of one location. Who we can correct it. to make sure if details not matches, just pass the dialed number with receiving calling mask.
That is what the default will do is just pass it out as it is if you don’t use an ELIN with that ERL. Default is only going to have the ALI info of whatever you put in there, so if you are using CER with a multi site environment you will want to consider carefully the possibility of calls using this pattern. Any call to the ER route point will be parsed regardless of what number you dialed initially. If you don’t use a ELIN then ensure whatever the destination is can accept or route the call with needed transformations, or the call will fail.
This is is based on my experiences operating a CER cluster so I again just suggest testing in your environment. You usually can contact your public safety dispatch and arrange to place test 911 calls to ensure the information is seen at your PSAP correctly. If you’re sending over your regular trunks you’ll need to make sure that you can assert the ELIN numbers and not just a main or billing number as well or it will also fail to route in selective routing.
