LLDP ELIN CID for 911 use

I have LLDP working with my Aastra 57i phones for auto VLAN provisioning. There is also a feature in LLDP for ELIN where the phone will change the CID to what is set on my switch if 911 is dialed. According to Aastra documentation

The 6757i IP Phone supports Link Layer Discovery Protocol for Media Endpoint Devices(LLDP-MED), and Explicit Congestion Notification (ECN) Emergency Location IdentificationNumber (ELIN). LLDP ELIN allows the phone to use the location information sent by the switch,as a caller ID for making emergency calls

Do I need to do anything in my outbound route, extension or trunk to allow this to work properly? All of our extensions begin with 1#### and they can dial long distance and 911 directly without using a prefix. I am in a small campus environment and each building has a different physical address. If I can set the emergency number this way, city/public 911 operators can properly determine where the call is coming from rather than it looking like the main building. Each building has an emergency DID associated with it with the correct address attached to the DID. I have tried the emergency CID under extension in the admin panel but that fails quickly when the user moves to a different building for a day and signs in with their extension (this happens quite often).

I would also like to see this option work. I work at a school that has 9 buildings on the campus and I just finished setting up a new FreePBX system. I have an emergency route set up that overrides the CID of the extension and sets it to the buildings E911 CID based on the emergency CID setting for the extension. This works great but my fear is that someone will take a phone to a different building and plug it in there and not tell me.

If I could use LLDP ELIN CID to automate the process of setting the emergency CID then it wouldn’t matter if phones are moved.

Another option would be subnet based location awareness. When a phone registers, the PBX could look at the subnet. From there DIDs can be associated with each to provide 911 operators proper location/floor if there’s an emergency. Also the CID that is used on the subnet could ring back to phones on that specific subnet in the event of a disconnect so operators can reach the person. FreePBX is very close to some enterprise systems out the market and this feature would put it even closer as a major contender.