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Large Scale Dial Peers


I am currently designing and infrastructure for Large VoIP deployment

One Central Site with a Voice Gateway with multiple Voice E1 Connection to the PSTN and over 600 Remote Sites Star connected to this Central Site.

Each Remote Site has an ATA with 2 FXS ports

when I used a Gatekeeper for a pilot for this project The 5 Pilot remote sites are registered along with the central Voice Gateway.

I am attaching the Show gatekeepers enpoints output.

In order to scale this solution for about 600 remote site.

what is the Gatekeeper needed for this scale?

Is it wise to use a Callmanager instead?

Please help.

Community Member

Re: Large Scale Dial Peers

I could not open the Gatekeeper text file.

Couple of questions to ask:

1) Do you ever plan in the future to use an IP phone?

2) Which type of ATA are you using? The ATA-186/188 can allow one call at g729 codec and one call at g711 codec, but not 2 g729 codecs.

3) what type of medium are the remote sites going over? Microwave, landline, satellite, etc?

If you are using a centralized model you might want to go with CallManager to make configuration and control a lot easier.

I have a simular deployment to what you are looking at.

We have multiple PRI's coming into 2 VGWs set-up as H.323 gateways. Both VGW's point to the CCM cluster. The call manager is set-up with Locations to provide the CAC for each of the remotes. We utilize IP phones (conference, speaker, and low end), ATA devices, FXS ports off routers, and remote routers connected to small PBXs.

Originally the system was designed with FXS and PBXs and then we moved to Call Manager based and added voicemail with Cisco Unity. Once the customer saw the difference with IP phones they really liked them. The ATA's are used Fax machinces at the remotes. Beware to use fax on ATA-186/188 you have to set line 2 to G711ulaw.

hope this helps.

Community Member

Re: Large Scale Dial Peers

Hi thanks for your answers,

however,this is the link for the ATA device

It is an H.323 endpoint.

No IP phones will be used in the future.

the Medium is Statellite.

So could the the CallManager handles 1200 H.323 FXS endpoint?

How about the Gatekeeper? how to size it?

I am re-attaching the file.

Community Member

Re: Large Scale Dial Peers

From the reading of their product this is an itme that would work with H.323 Gateway and Gatekeepers. In CallManager there is a menu option to set-up a H.323 Gateway. adding the IP address, CSS, and so forth. However, CallManager would probably be to hefty of a price tag for the connection of the DirectWay system.

The way the documentation reads DirectWay offers the Gateway and Gatekeeper already for your system.

If they based it on H.323 then Cisco will work fine for the Gatekeeper, of course that depends on how close to protocol standard Hughes followed.

As for H.323 configuration on Cisco follow this link:

That has configuration examples for the Gateway, Gatekeeper, IVR, etc.

Community Member

Re: Large Scale Dial Peers


Thanks again for the info.

I the problem now, is how do I scale the gatekeeper in order to support this high number of remote endpoints.

and still in case of CallManager, dis-regarding the cost, how can I size this number of H.323 endpoints?


Community Member

Re: Large Scale Dial Peers

Scaling for CallManager (CCM) would not be a problem depending on the type of CCM. With 600 remotes and two ATA's at each remote that would make 1200 devices total. According to the SRND for "Cisco Unified CallManager 4.x" you can only use 500 devices such as gateways. for a centralized solution. If you are talking distributed you can have 500 per cluster. see the link.

I cannot find any specific information that says this is the maximum number of Gateways that a Gatekeeper can handle. I did find some examples in how to set-up the Gatekeeper to gateway connection.

Cisco High-Performance Gatekeeper

If you run into problems expanding the number of ATA devices connected to the Gatekeeper you could always add more zones and then have selected gateways configured to register to specific zones.

Unfortunately you are using non-Cisco devices, which means that you have to either get Hughes documents or trial and error.

Community Member

Re: Large Scale Dial Peers

I agree the best solution is to use multiple Gatekeepers with multiple zones.

I can't speak to performance numbers and recommended Cisco routers model. What ever you choose I would max out the DRAM. I would look at either the Cisco 3800 or 7200 platforms.

Community Member

Re: Large Scale Dial Peers


Did you get an answer to this problem ?

I have a similar requirement for about 800 remote sites and I am trying to find out information about gatekeeper sizing.



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