I have one question in mind about the security of voice traffic over the LAN. I am using Call Manager 8.0. My Question is how secure and the level of security Cisco use in voice traffic. If someone use sniffer on my LAN so it will be able to listen voice or not.
Yes they will be able to listen to calls. By default the cluster only secures inter-server traffic. Authentication of signaling traffic and encryption of RTP streams requries additional effort. The Cisco Unified Communications Manager Security Guide, Release 8.6(1) explains your options and how to complete each portion of the work. Note that this is not a trivial task and should be done in a lab environment first. It's easy to break things when putting a cluster into mixed mode.
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.