Are you an experienced Tier 3 Engineer who enjoys solving meaningful technical problems instead of living in reactive chaos? Do you take pride in building stable, secure, well-documented environments that keep clients productive and protected? On Call Computer Solutions is seeking a proactive, client-focused Tier 3 Engineer to support and improve the technology environments of our managed services clients. This role is ideal for someone who can think beyond break/fix work, prevent issues before they become outages, and own escalations through resolution. The right candidate brings strong systems administration skills, solid communication, and the ability to balance daily support, proactive maintenance, documentation, and project work in a fast-paced MSP environment. You should be comfortable working across servers, Microsoft 365, identity, backups, virtualization, endpoint management, and core infrastructure while keeping security and client experience front and center. Key Deliverables / KPIs Proactively administer and maintain client environments, including Windows Server, Active Directory, Microsoft 365, Entra ID/Azure AD, virtualization platforms, backup systems, and core infrastructure; keep systems healthy, patched, monitored, and operating with minimal recurring issues and downtime. Own escalated support tickets and infrastructure tasks from diagnosis through completion, including root-cause troubleshooting, permissions, onboarding/offboarding, server maintenance, line-of-business application support, and small-to-mid-sized technical projects; document work clearly and communicate effectively with clients and internal teams. Improve client security and resilience by enforcing standards for patching, MFA, endpoint hygiene, backup verification, disaster recovery readiness, system documentation, and change control; identify risks early and recommend practical remediation steps that improve stability, security, and long-term service quality. Other relevant duties as assigned. Required Qualifications 3+ years of hands-on systems administration, infrastructure support, or MSP engineering experience Strong experience with Windows Server, Active Directory, Microsoft 365, DNS, DHCP, virtualization, backup/recovery, and endpoint management Working knowledge of networking fundamentals, including switching, routing, VPNs, firewalls, and remote access Experience with ticket-driven service delivery, documentation, patch management, and proactive maintenance Strong troubleshooting skills with the ability to communicate clearly to both technical and non-technical users

Preferred Qualifications

MSP experience supporting multiple client environments Experience with Azure, Entra ID, Intune, and cloud migrations Familiarity with business continuity and disaster recovery testing Experience working in security-conscious or compliance-driven environments Relevant Microsoft, CompTIA, or vendor certifications