Hi Daniel_Bae,
If you are referring to Lync 2010 then yes, the Lync Web App is supported on Windows XP SP3.
Please check the following prerequisites:
1. The Service Pack 3 is required for Windows XP to support Lync Web App.
2. The Microsoft Silverlight browser plug-in version 4.0 must be installed on your computer.
3. The sharing feature requires a plug-in. The first time users initiate a sharing session, they will be prompted to download the required sharing plug-in.
4. The Lync Web App is supported with IE 6 & 7 & 8 .
There are 3 audio support options in Lync Web App:
- Option 1: The conference calls you Lync Web App calls your phone or a phone number that you
type. (These settings can be changed in the Microsoft Lync Server 2010 Control Panel conferencing.)
- Option 2: Join audio using Communicator Available only if you have a client installed.
- Option 3: Dial in to the conference Dial in to the conference by using the phone number and
ID supplied.
For more details, please check out the articles below.
http://blogs.technet.com/b/nexthop/archive/2011/08/09/lync-web-app-overview-for-lync-server-2010-and-lync-2010.aspx
https://technet.microsoft.com/en-us/library/gg425820%28v=ocs.14%29.aspx
Best regards,
Eric