In Forrester's 29-criteria evaluation of enterprise on-premises unified communications and collaboration (UC&C) solutions vendors, we identified the 11 most significant providers — Aastra Technologies (acquired by Mitel in January 2014), Alcatel-Lucent, Avaya, Cisco Systems, Huawei Technologies, IBM, Microsoft, Mitel Networks, NEC, ShoreTel, and Siemens (rebranded Unify in October 2013) — in the category and researched, analyzed, and scored them. This report details our findings about how well each vendor fulfills our criteria and where they stand in relation to each other to help infrastructure and operations (I&O) professionals with telecom and networking responsibility select the right partner for their UC&C solutions.