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New Member

CER with Shared extensions

I have CCM 4.2 with CER 2.0. I have situations where I have shared extensions with 7940/7960/7921. I think that I'll have to manually enter the 7921s in since they cannot be tracked. I can't use subnet because there is only one subnet for wireless which spans multiple buildings.

Question is, will CER work with shared extensions? If I manually configure a 7921 in the system, with an extension that exists on a 7940, will there be conflict? They will reside in the same ERL.

Also, is there a way to just identify the port where the Access Point is connected to catch all my 7921 phones? Or must I manually enter them?




Re: CER with Shared extensions

CER can locate users to an IEEE 802.11b base station. But be careful, ay be on an adjacent floor!

Directional antennas limit this behavior.

I would go by subnets for the ERL location of the base stations if you can.

For Shared lines, its really does not matter because of the extension. It's the device that matters. CDP will gather the MAC address for each switch. Wherever you have the ERL defined by switch, the CDP will update the CER server. Example:

Extension 2000 is in the following locations:

- ERL Zone A

- ERL Zone B

- ERL Zone C.

Each zone has a callback number defined. Zone C Devce calls 911. CER knows to push the call out a certain CTI to CM that RP goes to gateway xyz. If the call is disconnected during the 911 all, PSAP will have the call back number identified from the ALI table you uploaded to them. They call back on Zone C call back number and it will ring all phones in each zone. It's because it's a shared line. You cant control that aspect unfortunately.

Hope this helps! let me know if you need more info

New Member

Re: CER with Shared extensions


How do I locate users to an IEEE 802.11b base station?


Re: CER with Shared extensions

If it's a cisco station, you can use CDP. If not you will have to congfigure it by CAM or subnets. The location in CER will be tied to the subnet. (so any devices on that subnet are associated to that zone)

New Member

Re: CER with Shared extensions

Just wanted to update you all.

I found that the 7921s do show up automatically, but in the unlocated phones section. They seem to grab the location of the base station, but I haven't been able to check 100%. You can either use that location, or assign it a location.

Also, shared extensions will work with automatically tracked phones since it's based on port location.

However, shared extensions do not work if you enter a phone in manually. I have noticed, in testing, this leads to unpredictable results. (or it uses the default location for conflicting information)

ATAs and VG224s are not supported. So, all analog phones must be entered manually.

One more thing as an FYI...CER uses one license per discovered phone in the Call Manager Cluster. So, if you are only wanting to support one site (say 1000 phones) but you have other remote locations on the cluster leading to 3000 phones, you MUST purchase 3000 user licenses in CER to support the phones. Even if you don't want to support them in CER. Yeah, customer is not so happy about that.

Re: CER with Shared extensions

Thanks for the feedback! That's what makes the forum rock! Cheers!

If they unlocated, you can set them to a CAM table based on IP address of the access point. (may need to update your network for this. Each access point should have it's own subnet for this to work in tracking)

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