This Competitive Assessment examines IMS and Evolved Voice Core for the "Big Five" vendors; Alcatel-Lucent, Ericsson, Huawei, Nokia Siemens Networks, and ZTE, which together supply 80% of the IMS market. In this report we examine the innovations and IMS portfolios of the firms and note particular features of special interest. Included are market share and vendor matrix assessments. This analysis is of interest to operators and vendors seeking to quickly gain insight into the different portfolios, and IMS Add-On suppliers seeking insight for their roadmaps.