Are you an admin or just the end user?
If an admin, then you should check the network (IP Routing, if you have a FW somewhere in the path, ...)
The green icon has nothing to with one-/no-way audio. It just says, if the softphone is registered or not.
If you are an end user --> talk to your network admins.
And: There are probably hundreds of post about audio issues and how to troubleshoot it.