Primary Responsibility: Serve as the senior technical escalation point for MIRATECH's US IT operations from our Tulsa, OK office, providing deep expertise in systems administration, network infrastructure and complex end-user issues that exceed the scope of the Level 1/2 help desk. The role acts as the resolver of last resort across US sites, partners with global IT teams on cross-region projects, infrastructure changes and security initiatives, and proactively improves the reliability, performance and security of core IT systems. By owning hard-to-solve incidents end-to-end and mentoring the help desk team, the Senior Systems Administrator keeps MIRATECH's US workforce productive and our infrastructure resilient. What You'll Do: The core responsibilities of this role include: • Serve as the Level 3 escalation point for the US Help Desk team, taking ownership of complex incidents that cannot be resolved at Level 1 or Level 2. • Administer and maintain core server infrastructure including Windows Server, Active Directory, DNS, DHCP, file and print services, Group Policy and virtualization platforms (Hyper-V). • Design, configure, monitor and troubleshoot enterprise network infrastructure including switches, routers, firewalls, VPNs, and Wi-Fi across US sites. • Manage Microsoft 365, Azure / Entra ID, Intune and other cloud and SaaS platforms at an administrator level, including identity, access, MFA and conditional access policies. • Support and harden endpoint security tooling (EDR / AV, MFA, patching and vulnerability remediation) and partner with security stakeholders on hardening initiatives. • Lead root cause analysis for major incidents, document findings and drive permanent fixes through to completion. • Plan and execute infrastructure changes, upgrades and migrations during scheduled maintenance windows, including out-of-hours work where needed. • Participate in a shared on-call rotation for critical incidents impacting US offices and escalations from global teams. • Partner with global IT teams on cross-region projects, standards and architecture decisions, and act as a senior point of escalation for international IT colleagues. • Mentor Level 1 and Level 2 technicians, develop runbooks and contribute high-quality content to the knowledge base (e.g. IT Glue). • Other duties as assigned. How to Qualify: The minimum qualifications required to perform this role are: • Education: Bachelor's degree in Information Technology, Computer Science or a related field, or equivalent professional experience. • Experience: 7–10 years in IT support or systems administration, including demonstrable time at a Level 3 / senior escalation level supporting business-critical infrastructure. • Technical Skills: Deep, hands-on expertise across Windows Server, Active Directory, Group Policy, Microsoft 365, Azure / Entra ID, enterprise networking (TCP/IP, routing and switching, VLANs, firewalls, VPN, Wi-Fi), endpoint management (Intune / MDM), virtualization (Hyper-V or VMware) and endpoint security (EDR, MFA, conditional access, patching). • Communication Skills: Excellent written and verbal communication; able to translate complex technical issues for non-technical stakeholders, write clear runbooks and lead incident bridges with confidence. • Organizational Skills: Ability to manage multiple priorities in a fast-paced environment, owning complex incidents end-to-end while balancing project work and mentoring of junior staff. • Other: Willingness to participate in a shared on-call rotation and perform occasional after-hours work for scheduled maintenance windows. What Sets You Apart: Optional qualifications that would make a candidate especially strong: • Industry certifications such as Cisco CCNA / CCNP, Microsoft AZ-104 / AZ-305 / MS-100, CompTIA Network+ / Security+, or ITIL Foundation. • Scripting and automation experience (PowerShell, Bash, Python) and familiarity with infrastructure-as-code tooling (e.g. Terraform, Ansible). • Experience supporting multi-site or global environments using RMM / PSA tooling (e.g. NinjaOne, ConnectWise Automate, ConnectWise Manage) and documentation platforms such as IT Glue. What We Offer: • Health, Dental & Vision Insurance • Annual Bonus Program • $350 Annual Wellness Credit • Flexible Spending Account (FSA) • 401k with match up to 5%