Connecting multiple CME systems

Answered Question
Sep 2nd, 2008

Hi i'm looking for a little clarification on an idea of mine if you don't mind.

We have a CME4.3 system up and running here on a 2801 and its doing just fine but i now have a requirement for a semi-isolated system in a lab enviroment that is going to require me to remove the phones in the lab's from the system but still give them voice connectivity, i am thinking about using a 2621XM that's spare from when we upgraded the systems as a CME router in that enviroment then setting up a link between the routers for voice traffic.

Having never setup a VoIP connection before i'm in need of some assistance with DSP's, can any of you confim that the DSP's in the routers are involved in CME-CME connections and that's just the way it is you can't get around it or is it possible to get a connection going without DSP rescources in the one router, the PSTN connection will be via the 2801 so i don't need the ability to connect VIC's to the lab unit or anything like that.

If DSP's are required in both i have a good case for investing in another 2800 series device but being a small company and also right in the middle of a new 2960 PoE rollout i'm looking for ways to keep the costs down.

Cheers

Dan

P.S Please excuse any spelling errors its been a long day.

I have this problem too.
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Correct Answer by Michael Owuor about 8 years 3 months ago

Hi Dan,

For CME to CME communication no DSPs would be needed. If your solution involves using voip dial-peers to allow communication between the two CME routers, the phones should handle communication between each other just fine.

You would need DSP's if:

- You require voice termination with analog or digital voice interfaces such as FXO, FXS, or PRI interfaces

- You require conferencing or transcoding

So if the lab router does not have any PSTN connection you would be fine.

The CME SRND also has a chapter dedicated to connecting multiple CME sites.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/srnd/design/guide/multcme.html

Hope this helps.

Regards,

Michael.

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Correct Answer
Michael Owuor Tue, 09/02/2008 - 15:37

Hi Dan,

For CME to CME communication no DSPs would be needed. If your solution involves using voip dial-peers to allow communication between the two CME routers, the phones should handle communication between each other just fine.

You would need DSP's if:

- You require voice termination with analog or digital voice interfaces such as FXO, FXS, or PRI interfaces

- You require conferencing or transcoding

So if the lab router does not have any PSTN connection you would be fine.

The CME SRND also has a chapter dedicated to connecting multiple CME sites.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/srnd/design/guide/multcme.html

Hope this helps.

Regards,

Michael.

computerman2001 Tue, 09/02/2008 - 16:16

Thanks very much, thats great news.

Sorry i did have a read of the design guide eariler today but i must have not been paying enough attention to the details with regard DSP's, will take a good look at it in the morning.

I figure i will use a dial-peer on both devices to do the routing, we currently use 1XXX numbers so if i put the lab on 2XX i think the config should be simple enough?

Any and all connections to the PSTN would be via the FXO cards in the 2801 that does contain the right kit for the job.

Thanks again for the help mate.

Michael Owuor Tue, 09/02/2008 - 16:40

You're very welcome Dan. Yes - dial-peers should do the job for routing between the two CME's. That's definitely a good idea you have there to use a different dial plan between the two. Do let us know how things work out.

Cheers!

Michael.

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