Did you try to check if the Callmanager and IP Phone are reachable? They should be reachable from both sides.Also check if the CallManager Service and the TFTP Services are running in the Control Center in Service Activation Center. Are you trying to auto-register the IP Phone if, so , check if the Auto registration is enabled in the Callmanager and the Callmanager group page.
For additional information, please refer to:
Troubleshooting Cisco IP Phone (7910, 7940, 7960, 12SP, and VIP30) Registration Problems with Cisco CallManager 3.x
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.