The only reason why I could not block yahoo / gtalk on my network was because of voice / video chat option. Redfire plugin for openfire can be used for audio / video chat. Follow below given procedure to enable openfire voice / video chat.
Plugin installation on Openfire server
download & install plugin in openfire
enable phone option in chat.
enable phone component in openfire server console –> red5
Plugin installation for Spark client.
download & copy red5 client plugin http://openfire-server:7070/red5/spark/red5-plugin.jar to spark\plugins |
TCP Ports required for plugin to function 1935 & 7070 apart from 5222