Extension Mobility and e911

Unanswered Question
Aug 26th, 2010

I'm pretty sure this is fundamental but I can't seem to find any info on this.  If a customer has a centralized HQ site (UC560) with multiple remote sites all on the same network.  How do I ensure that e911 will work when user is moving from site to site?

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antyeung Thu, 08/26/2010 - 14:30

Do you have a separate UC500 at each remote site or all the phones at the remote sites are registering to the central UC560?


Christian Isla Fri, 08/27/2010 - 08:15

This is why i'm struggling with this.  It is a centralized UC560.  From there the customer has multiple remote sites connected over fibre and the phones are all on the same network registered back to the centralized UC.   in terms of UC, it thinks that the phones are directly connected.  I know I can have e911 working if each of these phones at different locations had a different extension... (ie, 101 is Site A, 201 is SiteB, etc), but if the extension is the same because of EM, how does the UC know which site the user is calling from?  Is there a way to specify that the phone MAC is at another site?  How would that be translated?


antyeung Fri, 08/27/2010 - 08:54

Extension Mobility for the UC500 was not designed with that in mind. The assumption is that the phones registered to the UC500 are local to the box at a single site. Although you can deploy it the UC500 was not designed for a centralized dial plan.

If you want accurate e911 service with Extension Mobility with a centralized dial plan with multiple remote sites you may be better of researching CUCM. I believe they can do conditional routing for e911 based on IP address/subnet that the phones are registered with. But you may want to double check on that.



Christian Isla Fri, 08/27/2010 - 09:00

Has anyone been able to accomplish some sort of creative workaround?  What if the user logs in using a differnent profile at each site?  ie. siteA login 1113, siteB 2113, siteC 3113. Can that work?  what are the drawbacks to this?  Voicemail?? inbound outboud call routing?


antyeung Sun, 08/29/2010 - 17:53

To account for accurate e911 service the phones at each site would have to have different calling numbers. However, that defeats the whole purpose of having extension mobility if a user would have different numbers/profile for each site.

If you have different profiles for each site but each profile has the same number you'll have the same problem since it would appear that the calls are coming from the same number and you wouldn't be able to differetiate which site the call was coming from.