I recently had troubles to make webex work on my computer. The fact is that the application is not really meant to work on Linux and Cisco do not really support it on such a platform. After trying numerous solutions that works for other people, I found mine on askubuntu there.
Here is the trick:
$ sudo apt-get install openjdk-7-jre:i386 libxmu6:i386 icedtea-7-plugin firefox $ sudo update-alternatives --auto mozilla-javaplugin.so
And in case the previous doesn’t work (not my case):
$ sudo update-alternatives --set mozilla-javaplugin.so /usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/IcedTeaPlugin.so