I do not have 'Phone' tab in my WebEx Connect, so I cannot dial in to WebEx sessions which imples no audio during them. I've even tried different versions of WebEx Connect - always the same issue. What is stranger, all my collegues from work do have Phone tab. What is wrong, I cannot find any solution in the Internet?
The problem is that you are not connected to the corporate network where the CUCM is located. If you are remote, you will need to VPN into your corp network, then launch Connect. It will then register with CUCM as a softphone (if the admin has it setup for you). Hopefully in the coming months, Connect aka Jabber will have the ssl vpn client built into it and will automatically do this for you.