Extension Mobility and 911

Answered Question
Dec 21st, 2009

Hi All,

we have some users who are using extension mobility in multisite environment. How can I address 911 dialing if users login to phones in different locations. do I have to use Emergency Responder or it's something we can set it up without it?

any suggestion would be very appreciated.



I have this problem too.
0 votes
Correct Answer by Jonathan Schulenberg about 7 years 1 month ago

That is why the line CSS does not contain any route patterns. It only contains blocks for what the DN is not allowed to dial. All routing is done at the device CSS.

You may want to read the Dial Plan chapter of the UCM SRND for additional detail.

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Overall Rating: 5 (1 ratings)
Marwan ALshawi Mon, 12/21/2009 - 15:45

you mean you want users to use the local gateway of home gateway

i mean in a local gateway the gateway that is local in the site where the user loged in with EM at that time ?

Jonathan Schulenberg Tue, 12/22/2009 - 06:03

Emergency Responder should not be needed for this. You can do this using the line/device CSS approach. The concept is documented in the UCM SRND; however, the idea is that calling privileges are placed on the line CSS while all call routing is performed on the device CSS. In essence the line CSS ends up being only a list of blocked route/translation patterns of what that DN is not allowed to dial. The phone is configured to route all calls appropriately to it's physical location (which can be dynamic if using device mobility). Since the line CSS takes precedence when a match is found in both, the user will be denied if their line CSS has the block present.

As a side note, if you do not have this already, I presume you have only a single CSS on the line or device. Moving to the line/device CSS can be a moderate undertaking. You may also want to evaluate the new E.164 dial plan design introduced in UCM 7.0. This builds upon the line/device CSS model but is implemented fundamentally different in UCM. This is also documented in the UCM SRND but does take a while to understand.

Lastly, there is a limitation with the line/device CSS that could be a minor nuisance: the calling privileges assigned to the line CSS are not aware of their location at any time. This means that if you prevent a user from dialing long distance, the line CSS has no way of updating to know what "long distance" is when they roam to another site and login using extension mobility. They would still be restricted to dialing local calls from the perspective of their home site even though those would now be long distance. If you are in the United States, Canada, or parts of the Caribbean this is mitigated by the NANP. This is because NANP is a fixed-length dial plan which allows you to place restrictions based upon the dial string length (i.e. local is seven digits, long distance is ten digits, international starts with 011, etc). If you are elsewhere in the world or if you want to use the E.164 dial plan design, you loose this predictability.

alex goshtaei Tue, 12/22/2009 - 09:12

Hi Jonathan,

if line CSS take precedence over phone CSS, so if the user move to roam location, still line CSS will be applied and it chooses home gateway.

very appreciate for your response.



Marwan ALshawi Tue, 12/22/2009 - 15:06

if you are using CUCM 7.x you can archive the same but with less CSSs and partitions using local

gateway approach

Jonathan Schulenberg Tue, 12/22/2009 - 15:09

Right, the Local Route Group feature is an awesome improvement of UCM 7.0+. Just be careful that you clearly understand the details of the line/device CSS concept and how calls will route before you add the wildcard that is LRG into the mix. Remember that the https:///dna is a great tool at your disposal to understand what UCM is doing.


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