This video shows the configuration of our voice gateway with the commands "call-manager-fallback" and "ccm-manager fallback-mgcp." From there we turn off the callmanager service on the callmanager and have a physical ip phone fail over into SRST mode along with the voice gateway failing over to mgcp fallback mode. We then start placing calls between our failed-over cluster and our callmanager cluster that is still communicating with its callmanager.
Let the fun begin!!! :-)