It is possible to replace your Microsoft Lync client by a free IM client : Pidgin with a special enabled-plugin : SIPE
To download the latest win32 Pidgin version :
Download the SIPE plugin compiled for Windows :
Then, install your new IM client by launching the installer. Do the same for the SIPE client. Now, add your Lync account into Pidgin by providing the following information :
Protocol : Office Communicator
Username : your professional email address
Login user : your_firm_Active_Directory_domain_name\your_windows_login_name
and that’s all. For your first connection, you will be asked to enter your AD password and probably to accept some security certificates. No further configuration needed. It should work out of the box.