Microsoft tests and qualifies phones, headsets, webcams, conference room devices, PCs and other devices for Lync under its Compatible Devices Program. This program has 2 levels:
'Optimized for' phones for desk, common area, and conference rooms powered by Lync Phone Edition & Other compatible IP phones 1.
'Optimized for' phones, wired and wireless headsets, handsets, and webcams.
PCs 'Optimized for' Lync.
'Optimized for' IP conference phones, speakerphones, and video conference systems.
1Always check if your Lync version was tested with the interoperable IP phones available.