911, multiple addresses, and moving phones.

[Dragons]

So my organization is having issues with 911 (emergency) calls getting matched with the correct street addresses at the PSAP. We have a large Municipal Area Network with 30+ physical locations and regularly people move their phones without our knowledge and breaks the way we handle 911. I don't like getting calls about first responders showing up to the wrong building.

For context let me explain how we handle 911 on 3CX currently:
There is an extension group for each physical location
A majority of phones at each location do not have external DIDs but can make external calls
There is a 911 outbound rule for each extension group that gets matched with a corresponding SIP trunk that routes the call to our normal gateway but with a unique SIP User ID.
The call gets past to a Cisco CUBE router (from an old CUCM install) that really doesn't do anything but forward it along to our providers Adtran router.
Our PSAP uses that number to look up physical address info in their database.
I have a good relationship with our PSAP as we regularly renovate, sell and buy buildings that require database changes.

This works great for 90% of our buildings but our issues arise from large campuses of buildings that are close together yet have different addresses. No matter how many times we warn people not to move their phones without letting us know, they still do it and the phone/extension is now in the wrong extension group for the building its in and will now report the wrong 911 address. Phone moves happen about 30 times a month and many of them are not reported.

Yes, I could wash my hands of it, point to emails and say "I told you so", however many of our locations have children in them and I wouldn't feel like a real human being if I didn't look into a better way of handling 911.

To me, in a perfect world, I would be able to assign 911 info based on an end user's phone (Yealink) or softphone based on IP address as IP schemes are unique to each building.

Any thoughts?

 

[sip.bg]

Forbid calling 911 from these movable phones.
They can use their mobiles instead (free of charge or even without SIM card).

 

[Brian Cross]

Create separate trunks per location. Then define which group is allowed to dial out which trunk. Seems much easier than what you got going on albeit it is working and all.

Won't fix the issue with people moving the phones however. That is a people problem not an IT problem.

 

[accentlogic]

I like the idea of creating an outbound rule based on the device IP address/subnet. You might want to post that in the Ideas forum.

To prevent desk phones from moving I suppose you could use DHCP MAC address filtering, where the phone VLAN only gives an IP to authorized phones. Force the phones to the phone VLAN by OUI, so that when any Yealink or other phone connects it is forced to your voice VLAN, and then use DHCP MAC Address Filtering to only give an address if the device is in the list. That way, when a phone moves to an unauthorized subnet it just won't work until they contact support to get the MAC added and the location changed for e911. Probably a lot of work, but like others mentioned above I don't see any other way to prevent them from moving.

Of course, maybe having all users with phones sign a form stating they understand they are liable for 911 charges due to an invalid address and liable for any injury or death resulting from the incorrect address dispatch would get their attention...