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New Member

CallManager Express redundancy

We have a client with 120 users and are going to install CCM or CME.

If we go for CCM, we are going to implement two servers. One Publisher and one Subscriber. We will use Publisher as a secondary subscriber which is a typical redundancy scenario.

If we go for CME, we are planning to implement two CME. Thus half of 120 users (60 users) will register to CME 1 and another half of 120 users (60 users) will register to CME 2. We are also planning to have a third router running as a PSTN gateway.

Question is whether CME can provide a full redundancy scenario? In our case, if one CME 1 is down, 60 users will lose their voice communication. Is it possible to provide a full redundancy scenario in CME environment.


Re: CallManager Express redundancy

yes, CME can be configured for redundancy using SRST.

CUE is not possible if you use that as well.

see the following link for CME SRST config:


Re: CallManager Express redundancy


well i know ccme 4.0 can provide redundancy by configuring a secondary IP under telephony-service, prior to that we used HSRP for redundancy. however, your sharing load with two CME system. how come you didnt just let everyone register with one CME and use redundancy to register with the backup in cases of failure?( id think this might be full redundancy). the third router is fine, just obviously needs connection path to both systems.

New Member

Re: CallManager Express redundancy


Found this in CCO.

and it seems like it can do CME backup starting from CME ver 4.0.

What we plan to do now is to install three routers: one primary CME, one secondary CME and one PSTN voice gsteway with a voice T1 circuit. The only question I have now is the voicemail. An external Unity server needs to be installed. I guess it is doable, but would like to confirm if anyone has experience to set this up. Thanks.


Re: CallManager Express redundancy

Well i you still have two options with the voice mail as well.

install a NM-CUE (can now support up to 240 VM i think)or as you said integrate with an existing UNITY server.

note the first option is platform dependent.

and failover is not supported CUE