Lync 2013 introduced a new Lync Web client that is amazing. It has very similar capability to the Lync desktop client and is used to allow participants outside your company to join a Lync meeting. You just need to send them a Lync meeting invite. When they receive it and click the “Join Lync Meeting” link, a web browser launches and then they are prompted to join the Lync meeting. A small plug-in (~7MB) is required to get the full capability.
A common question that comes up when I talk to customers is: “Does the user need local admin permissions to install the plugin?” In this blog post, I tested the client and determined that local administrative permission are not required to install the Lync Web App plug-in.
A step by step walkthrough of the test is attached: Lync 2013 Web App