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Quick Caller ID Question

In lab testing a while back, I noticed a strange quirk that I wanted to throw out here to see if I'm on the right page for Caller ID. It's fairly simple, but I remember in lab tests it was not working the way I had planned.

Basically the scenario is two buildings side by side with 200+ phones in one building deployed, and about 20 more phone deployed in the building next door. The two buildings are connected via MMF, and all the phones from B2 register with CCM over the MMF to the head end. In the head end there are two PRI's off a 3640 for PSTN access.

For 911 purposes the head end building needs to display 555-2700 out to the PSTN. The 2nd building needs to display 555-2800 out to the PSTN so that Emergency responds to the right building.

My plan was to configure the CCM H.323 gateway's Caller ID field with 555XXXX first off. Next the plan was to have all phones in the head end building have an external phone mask or outgoing caller ID pattern programmed in as 555-2700. And in the second building those phones would be programmed with 555-2800.

The theory would be that the Caller ID information from the phone would pass out through the gateway with either 555-2800 or 555-2700 depending which phone made the call. The problem I had a ways back in the lab was that this was not working correctly for some reason, unfortunately without having the gear in front of me at the moment I can't get any more specific on what was happening.

Am I off base on this theory, or can anyone shed some light on the topic? I'd be interested to here any production situation examples.


Cisco Employee

Re: Quick Caller ID Question

Yes, I can see what you were trying to accomplish, and understand what you configured to do so. However this is not the best approach to use. I usually recommend against configuring the Caller ID field on a gateway, because it offers the least amount of flexibility. Also note that as far as calling number transformations, it is the last one to be performed for an outbound call, which means that it will override or be combined with any other translations you are doing, which can confuse the issue and produce undesired results.

There are certainly a number of ways to accomplish what you want to do. Perhaps the way that gives you the most flexibility is this:

- Create 2 partitions: B1Emergency, B2Emergency

- Create at least 2 route patterns: something like:

9.911 in partition B1Emergency (calling party transform mask 5552700)

9.911 in partition B2Emergency (calling party transform mask 5552800)

and both of the partitions should not have the "use external phone mask" checked

- Create 2 calling search spaces, one for each building, for example: B1_CSS (includes B1Emergency partition) and B2_CSS (includes B2Emergency partition)

- Assign the calling search spaces to the phones in each building.

- Make sure you remove the Caller ID field from the gateway(s) and reset it

- For other route patterns, you can use the "use external phone mask" checkbox if you wish.

Now, for "regular" route patterns, if you use the external phone mask from the phone line, that is the caller ID that will be sent out to the PSTN. For calls to 9.911 (or whatever patterns you configured for emergency access), the phone will match the route pattern for the appropriate building's partition, and instead of the external phone number mask being used, we will use 555-2700 or 555-2800 depending on which route pattern was matched.

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