Senior System Administrator - Warszawa

Senior Telco Infrastructure Administrator

Location: Warsaw, Poland
Working mode: Hybrid

About the role

We are looking for an experienced Senior Telco Infrastructure Administrator to join a team responsible for maintaining and developing mission‑critical SaaS and telecommunications infrastructure. In this role you will manage highly available production environments, optimize system performance, automate operational processes, and support modern VoIP platforms across Linux infrastructure, networking, virtualization, and cloud technologies while contributing to the evolution of scalable and resilient platforms.

Key Responsibilities

• Administer, maintain, and develop Linux-based production infrastructure.
• Ensure high availability, scalability, and performance of mission‑critical systems.
• Manage virtualization, containerization, and infrastructure automation.
• Maintain monitoring, logging, and alerting platforms.
• Support and optimize VoIP and telecommunications platforms.
• Design and maintain network infrastructure, including routing, VPNs, and firewalls.
• Troubleshoot complex production incidents and implement long‑term improvements.
• Collaborate with engineering teams on infrastructure modernization and architecture initiatives.

Qualifications

• Strong experience administering Linux environments (CentOS, Ubuntu, Debian).
• Hands‑on knowledge of virtualization technologies (KVM) and container platforms, including Proxmox, OpenVZ, or K3s.
• Experience with Nginx, PostgreSQL, RabbitMQ, Redis, Consul, Elasticsearch/OpenSearch, and similar production technologies.
• Practical knowledge of monitoring and logging solutions such as Zabbix and Graylog.
• Experience supporting VoIP environments, including SIP, Kamailio, FreeSWITCH, SBCs, AudioCodes, or FreePBX.
• Solid networking knowledge, including BGP, OSPF, VPNs, firewalls, QoS, and platforms such as VyOS, Juniper, or MikroTik.
• Strong troubleshooting and problem‑solving skills in production environments.
• Experience with Microsoft technologies, cloud platforms (Azure or GCP), Hyper‑V, WebRTC, or 3CX will be considered an advantage.

Offer

• Employment based on an employment contract or B2B agreement.
• Competitive salary of 20,000–25,000 PLN/month, depending on experience and employment type.
• Opportunity to work with advanced SaaS and telecommunications infrastructure.
• Real impact on infrastructure architecture and technology decisions.
• Flexible hybrid working model after onboarding.
• Stable, long‑term cooperation in a highly skilled engineering team.
• Professional development opportunities and exposure to modern cloud, networking, and VoIP technologies.