There have been questions regarding the possibility to add a second subscriber to an existing Pub - Sub pair of callmanagers on BE6K platform.
If we look at the BE6K FAQ it provides conflicting information
http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps11369/qa_c67-703226.html
Table 1 says it's limited to single or dual nodes.
However, further down it contradicts:
Q. Does Cisco Business Edition 6000 support more than two nodes in the cluster?
A. Yes, you can deploy Cisco BE 6000 with more than three nodes in the cluster as long as the user count does not exceed 1000 users.
Now, the callmanager SRND states the following
Cisco Business Edition 6000 may be deployed using the clustering-over-the-WAN call processing local failover model. In this type of deployment, two Business Edition 6000 server nodes are deployed at each of two sites to provide geographic redundancy for the Unified CM call processing application. The two Business Edition 6000 server nodes may both be UCS C200 Rack-Mount Servers, or alternatively one of the servers may be a regular Cisco Media Convergence Server (MCS).
Answer : As per BU you may deploy more than two nodes when using BE6K so long as you do not exceed the maximum user and device counts that is supported on this deployment model.
