porting numbers

Unanswered Question
Jun 3rd, 2008
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Hi all. I have a question I cant seem to get right in my head on how this should work. Im trying to figure out how to implement a potential solution. I have a potential customer that wants to put in a CUCM and they have 4 sites total. One main site, with three remotes (all in separate states). Im wondering if all of them have their own phone numbers now (i.e. (555)555-5555, (444)444-4444, etc). How would you go about keeping their phone numbers, and having them routed to the right location? I was thinking something like PRIs coming into the main site, but not sure how you would keep the phone numbers the same coming into one site, since they are all out of state from each other. Or, if they all have their own PRI, how do you get them to come into the callmanager from each site gateway? Any ideas on how to do this? Thanks.

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Overall Rating: 4 (2 ratings)
Michael Owuor Tue, 06/03/2008 - 12:27
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Hi John,

Some thoughts on your potential solution...

It is usually possible to have the numbers ported to a PRI at each location. Your local PRI provider at each location should be able to confirm that.

Part of the planning of a unified dialplan would be to determine how many digits to use for the extensions on the phones. Here you'll make some assumptions such as expected future growth and the need to avoid an overlap in the internal dialplan. Put a lot of time here and create a scalable plan.

So for example if you decide that you'll go with a five-digit internal dialplan, then you could proceed to register the extensions, eg:

- SiteA - 5XXXX

- SiteB - 4XXXX

- SiteC - 3XXXX

Since they would be registering to the same CallManager cluster, there's nothing else to do to allow inter-site dialing. UserA1 at SiteA can simply pick up his phone and dial 44444 to reach UserB1 at SiteB.

Configure the gateway at each site to support the chosen dialplan. For example, if you go with 5 digit extensions, configure the gateway to ignoring all but the rightmost 5 digits. Alternatively, while provisioning the PRI circuits, work with the friendly local carrier at each site to have them only send the 5 DIDs on inbound calls. You'll also configure each gateway in CallManager, and when a call comes into it, each gateway hands the call control to the CallManager which rings the appropriate phone.

You'll also plan other aspects of the dialplan such as classes of restrictions (CSS's and PT's), least cost routing, and redundant routing.

Hope this helps.



jjoseph01 Tue, 06/03/2008 - 13:14
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Thanks for responding. So, since they all have a PRI at each location, the call coming in from a local person can call in on a PRI at one remote location, the call be forwarded over to the CUCM, and the call be pushed back over the the internal DID number? AND a second remote site can do the same for it? Am I see this correctly in this way? Im trying to find a document on how to configure that, but cant seem to find one. Any of you guys know of one in particular that might be good?

Michael Owuor Tue, 06/03/2008 - 13:42
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Yes, a call coming into a PRI at a remote site will be handed to the CUCM via the signalling protocol between the gateway and the CUCM. The CUCM will then cause the phone to ring via the signalling protocol between the CUCM and the phones. That the phones are located at a remote location is transparent to the CUCM, as long as there is IP connectivity between the sites.

The Solution Reference Network Design document has a chapter on Deployment Models, which includes the 'Multisite WAN with Centralized Call Processing' model.


Hope this helps.



jjoseph01 Tue, 06/03/2008 - 21:26
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Thanks all for the help. I just need to figure out how to configure it. Thanks for the guidance.


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