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New Member

CME HA questions

Hi All,

One of my client requested a CME with unity express for below mentioned requirement.
- 100 ip phones to be installed in 8 branches.
- All these branches are connected by MPLS.
- He wants to have voice Mailbox for 100 users with Auto attendant.

However he does not have  plan to connect CME with PSTN network and effectively
he wants to use CME only for Onn-net calls (between offices over the mpls link).

so far so good , but he also wants CME's HA ( 2 cme routers) .

My questions are pertaining to CME redundancy.

- Can i provide call processing failover , for instance if    primary CME down then Secondary
   CME will takeover the registration    of ip phones ?
-  I am convinced with the fact that i don;t require SRST on primary/secondary CME.
   As both the routers would not be connected to pstn network ?

-  Can i provide voice mail failover and Auto attendant failover also with 2 CME's?
-  If we create HA between two CME do we have to buy 100 user license for both CME?


New Member

Re: CME HA questions

CME does support HA by haveing 2 of the same routers and using HSRP between the routers.  This will require you to make sure both routers have the exact same configuration.Any changes made on one must be made on the other.  You will need to buy and licencse cme for both boxes.

There is no HA for CUE.  i would recommend using Unity Connection at one site in HA and then you can put ISM modules with unity survivability at every site to Archie what you are looking to do.

you could have a CUE on the backup CME and just have you AA setup but you cant have any voicemailboxes on there.  If the HSRP fails over for any reson you phones will work but your voicemail for users wont.

bottom line is CUCM is a better fit for you with SRST routers.

New Member

Re: CME HA questions

thanks . that explains. just concluding with my present configuration

i cannot provide unity failover. but i can provide call processing failover

and AA failover.

New Member

Re: CME HA questions


All HA on CME is not soo clean

Expected Results


Configure HSRP between the two Cisco 3825 and two Cisco 3845 Integrated Services Routers. IP phones should register with the virtual HSRP IP address, which is tied to the primary voice routers. IP phones must reregister with the backup router.

Verify IP phones will reregister with the Cisco CME on the backup router after the master HSRP router goes down. Also verify PSTN trunks failover.

The IP phones were registered to the primary Cisco CME router and failed over to the backup router. The failure was simulated by pulling the electric plug on the primary router.