I have CM verison 6.12,
the cisco docs say this can now support Extension Mobility Redundancy. How exactly does this work? DO I have to configure the EM service on both my CMs and set an ordered list? or have two EM services (one for each of the CMS) or do you have to use SLB on a router?
You've obviously read the documentation on the SLB.
I've never configured it but the easiest and quickest way of configuring redundancy for phone services is to create an additional IP phone service pointing to another server in the cluster which can be used by everyone to switch over in the event of server/EM failure.