basic Qs on call routing in CCM

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Apr 4th, 2007
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it may seems that it is very basic questions but since it's the first time i'm dealing with this stuff:

if i have let's say E1 (30) telephone lines from telco terminated on 2821 mgcp gateway, with ccm environment, now how the incoming calls to local phones would be handled, i mean if someone calls from outside to whom specifically this call would be routed?

what governs this routing to internal phones?

the route patterns are built just only for external calls originated from internal phones? right?

what if want to restrict this phone number (specific one channel among these 30 channels) to go specifically to that local phone extension? is this the DID functionality and is this how it is configured on ccm?

please ur help in clarifying these points

many thanks

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Brandon Buffin Wed, 04/04/2007 - 12:15
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CCM will look for a route pattern, translation pattern or DN that matches the digits sent by the telco and accepted by the gateway. You can determine the number of digits that CCM looks at by setting the Significant Digits in the gateway configuration. If siginificant digits is set to 4 and CCM receives 123-555-1212, it will look at 1212 and route the call based on this. If significant digits is set to All and the telco sends you 123-555-1212, CCM will look at this whole string and route the call. In this case, you could have a translation pattern that matches 123-555-1212 and translates the called number to 1212 or any other number you like. This gives you a couple of ways to implememt DID depending on whether your DID numbers match internal extensions or not.

Hope this helps. If so, please rate the post.


user-cisco Wed, 04/04/2007 - 12:57
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thanks Brandon, u said that CCM will look for a route pattern, then do i have to configure route patterns so that incoming calls from pstn would match these route patterns, and so how to cover all pstn possible calling numbers to be matched with one of route patterns to be built for this prupose!! as i know route patterns are configured and added to ccm just only for outbound calls originated from local ip phones. please correct me if i'm wrong?

what if the gateway is mgcp, as i know there is no config regarding call routing made on mgcp gateway, it just passes to ccm? right?

also in either E1 or fxo i know there a required field which is an attendant DN u should assign to a specific fxo port this means that it will ring just only this DN if this is correct then what does the route pattern, TP match have to do in this case

i appreciate if someone high some lights on these points


Brandon Buffin Wed, 04/04/2007 - 13:13
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A route pattern would only be necessary if the incoming call were being routed back to the PSTN or across a trunk for whatever reason. Also, this would match on called number, not calling.

Correct, with MGCP, the call routing intelligence lies with CCM.

With FXO, the Attendant DN field is required because only one call with one called number will be coming into this port and it needs to know where to route the call. This field is not required for E1. With E1, many calls with many called numbers can come into the port, so CCM will route the call based on the called number. If the called number matches a DN, no translation is necessary. However, if your DID numbers do not match internal extensions, you will want the call to match a translation pattern which will translate the called number to one which does match a DN.

Hope this helps.


user-cisco Wed, 04/04/2007 - 13:36
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just 2 things:

first, when u said A route pattern would only be necessary if the incoming call were being routed back to the PSTN, how this happens and what scenarios this would occur?

second, (With E1, many calls with many called numbers can come into the port, so CCM will route the call based on the called number), so who will do the first digits stripping and where? (imean in mgcp case) assume that all local DN's are of 4 digits and the dialed number from pstn is the full number (of 7 digits for example)?

thanks Brandon again for ur help

Brandon Buffin Wed, 04/04/2007 - 14:24
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One scenario where a route pattern would come into play is if the incoming call was to be routed across an intercluster trunk. In this case, the call would match a route pattern which would point to an ICT and be routed to another cluster. This is just one example.

CCM would do the first digit stripping based on the Significant Digits field in the gateway configuration. If it is set to All, no digits will be stripped. In the case of 4 digit extensions, you could set this to 4 and the call would be routed to the extension that matches the last 4 digits of the called number. This is assuming the last 4 of your DIDs match your internal extensions.



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