CUCM Subscriber Design Question for remote sites

[dan hale]

I'm helping migrate a customer that has an old digital PBX to possibly CUCM. In the design process they have 9 sites connected via WAN links.

My ultimate goal would be to put the Publisher at the primary site with the PRI and have the phones register to that and have a subscriber at each site to have the remote sites register to the local CUCM. My reasoning for this is that if the WAN link goes down the Phones can utilize several POTS lines we can use at each site. Until the WAN link is reconnected.

My problem is that based on my research that I can only have 8 active call processing nodes but, up to 20 CUCM servers just not all doing call processing.

"A Unified CM cluster may contain as many as 20 servers, of which a maximum of eight call processing subscribers (nodes running the Cisco CallManager Service) are allowed. The other server nodes within the cluster may be configured as a dedicated database publisher, dedicated TFTP subscriber, or media resource subscriber."

What options would make sense in case the WAN link goes down....I know that I could possible use SRST but, if I could get a subscriber at each site it would be less work programming wise.

Any suggestions...

Thanks,

Dan

[Jaime Valencia · Accepted solution]

You can have more than 8 servers running CUCM service, that's a mega cluster, but in order for those to be officially supported by Cisco, they need to be reviewed and approved by the mega cluster team, engage your SE/AM for information about this.