When it comes to replacing your existing PBX system with a UC solution, challenges include:- Changing users' behavior to align with new workflows, capabilities, and standards- Understanding and gaining visibility into current system usage- Accommodating various technical and business requirements for all users and customers across all departments and lines of businessEnterprises need a trusted service provider that partners with their organization throughout the entire UC lifecycle - from defining business requirements to solution design and deployment to ongoing enablement and day-to-day management. This paper will outline six critical criteria that every enterprise should evaluate when choosing a UC service provider.