IP phones and 911

[KarlJVT]

If you're running a VoIP system, how do you keep people from moving their phone to another office without you knowing? Changes have to be made for 911.

 

[HmmG3]

Does each location have its own dedicated IP subnet? For example, our building 32 has IP addresses that start with 10.32.x.x while building 33 has 10.33.x.x addresses. If you have something like this setup, then you can list phones by their CSS and see if any of the phones are in the wrong subnet.

While I've never done this, CallManager 4.2 allows you to define a CSS by IP address. So if the user moves their phone to a different location, it should automatically switch to using the new location's local gateways.

 

[KarlJVT]

No, we're running DHCP so it just pics up an address automatically. I thought about using a restriction like that... Just wondered if there was an easier method.

 

[HmmG3]

Our network uses DHCP as well. We just use different scopes and subnets between each building. Without different subnets, there's just no way of either you or the CallManager to tell where the phones are located.

If you have a 24/7 security desk, you could just redirect 911 calls to them. We do this at some locations. They would know where the user is located as they have all facility records there. They would also be able to respond faster to the location while contacting 911 directly for additional emergency services.

 

[IPTG]

What about port security on the switch.