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Antonio Morales

How an H.323 GW can setup a call to devices with different Device pools (cluster over WAN)?

Hi all,

Im on the situation right now where I have to configure CUCM for a new office we are openening.

My current configuration is as follow :

Current Configuration

Callmanager Group HQ_CMG

Device Pool HQ_DP

HQ IP Phones [HQ_DP]


On this new office we are going to deploy a subcriber (UCMSUB02) for clustering over WAN, so I will create New Callmanager Group (BR1_CMG), new Device pool (BR1_DP) and add phones using the new device pool (BR1_DP).

Configuration to add

Callmanager Group BR1_CMG

Device Pool BR1_DP

BR1 IP Phones [BR1_DP]

At the end my infraestructure will look as the diagram below.

Sounds easy, but my complications come with the H.323 Gateway we have. This H.323 GW is configured to use HQ_DP with HQ_CMG Group meaning that GWY01 can only dial UCMSUB01 and UCMPUB00. What Can I do so this GWY01 can also dial UCMSUB02 on BR1?

Help Please

paolo bevilacqua
Hall of Fame Master

By configuring the dial-peers appropriately.

Thanks for the reply,

But thing is your dial-peers can only target a callmanager server that is member of the Callmanager group you assigned to that GW.

Ussing the information provided on the original post, GWY01 is configured with HQ_DP(HQ_CMG[UCMSUB01 | UCMPUB01]) the dial peers on the Gateway can only setup a call with UCMSUB01 or UCMPUB00 if you configure a dial-peer targeting UCMSUB02 on BR1 the call will faiil with and Internetwork Error.

No, an H.323 GW can target anything you want.

Thanks Paolo,

Have a Lab? Try it, call will be rejected.

It is like you configure a GW's dial peer to target a CCM server but you do not configure the CCM Sever referencing the GW.

You will get a busy tone.

Ok, so you know more than me.

And the next logical conclusion is that you must configure CM to accept calls into any cluster member for that to work.

And the next one is, if you can't do the above, then what you want can't be done.

Antonio Morales

Please do not take me wrong,

You have a lot of experience on this, Do Im wrong on what Im saying?

I was on the same though than you, but about 6 month ago  when we schedule a maintenance and we took the subscriber down the dial peers targetting another server on the cluster failed to setup a call, the reason was that the server was not a member of the CM group used by the GW.

Im posting looking for help and any input is highly apreciated, I need a solutio or work around.


Again, to my knowledge, an H.323 GW can send calls to any CM cluster member. That is key to achieve redundancy.

If the above is not working for you, recommend you contact the TAC.


Read about H.323 Operation in CallManager:

Hope it helps, please rate if it does.

-- Adrian.

Thanks Adrian, by coicidence this is exactly what I was reading and it proves the Issue Im facing.

I need a Work around or solution for this situation. At this moment we are adding this new office but plans are we will consolidate the other clusters on this one and I will run on same situation as this new site.

Im thinking about GKs but this is no a solutuion for me right now becuase Im running out of time and like this I have 3 other GWs taking thousends of calls at day, So I need time for better planning and testing, GW reconfiguration to point to GK, etc.

Thanks again.

Thanks Paolo,

Just to complement, you are right on the statement that the H.323 GW can setup a call to any CM cluster member for redundancy, but that redundancy is controlled by the CM Group.

While I was writting this I did a reasearch and here is adocumentation that supports what Im saying.

For devices using Unified CM Groups, it is important to know which nodes will run H.225 daemons because calls sent to an incorrect subscriber might be rejected. For example, this situation would occur if a Cisco IOS H.323 gateway is configured with dial peers that send calls to subscriber C in a Unified CM cluster but the Unified CM Group for that gateway has only subscribers A and B in its list. In such a case, the call will fail or be handled by an H.323 trunk daemon if one happens to be configured on the subscriber.

Inserted from <>


A CallManager group can contain up to three servers so would adding the remote subscriber to the HQ DP be an option?

If you did not want the HQ phones to use the remote SUB then you could set up a DP just for gateways.

I think I might be missing something because this answer seems so obvious

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