We are a European telecommunications company with a long-standing background as an ISP dating back to 1998. Since 2011, our core focus has been VoIP services, including call origination and termination, as well as global DID (virtual number) solutions. 

Our infrastructure is fully self-operated and built largely on open-source technologies. We run our own ASN, maintain BGP connections with upstream providers, and manage physical infrastructure across data centers in Germany and Switzerland. 

Our small, experienced technical team is developing new web-based telecom services, and we’re seeking a hands-on engineer to take full ownership of our infrastructure and drive its evolution. 
 
Remote • Part-time (4 hours/day) • Freelance • €1,000/month 
 
The Role 

This is a hybrid System Administrator / DevOps / VoIP Operations position with end-to-end responsibility for our production infrastructure. 

You will serve as the primary technical owner of the platform, ensuring stability while leading the gradual modernization of legacy systems. This role is ideal for someone who is comfortable working independently, making pragmatic technical decisions, and operating in live production environments. 

Key Responsibilities 

• Own and maintain Linux servers and virtual machines
  
  
• Plan and execute migrations from legacy platforms
  
  
• Operate and enhance the VoIP stack (Asterisk, Kamailio)
  
  
• Provide infrastructure, tools, and environments for development teams
  
  
• Evaluate and integrate new VoIP vendors and SIP interconnections
  
  
• Diagnose and resolve routing and customer-related issues
  
  
• Improve automation, monitoring, backups, and security posture
  
  
• Support basic network operations (BGP environments, routers, switches)
  
  

Current Environment
 
Infrastructure
 

• ~26 physical servers and ~40 virtual machines
  
  
• Additional VMs hosted with external providers
  
  
• Primary location in Frankfurt with two sites in Switzerland
  
  
• OS mix: CentOS 6/7 (majority), Ubuntu, and one legacy FreeBSD VM
  
  

Core Software Stack
 

• MySQL, MariaDB, Galera Cluster
  
  
• Asterisk, Kamailio
  
  
• Apache, HAProxy, Varnish
  
  
• BackupPC
  
  
• tinydns, dnscache
  
  
• Nagios
  
  
• Joomla

Hardware & Networking
 

• Supermicro servers with IPMI (KVM-over-IP)
  
  
• QNAP NAS storage
  
  
• Juniper M-series and SRX routers
  
  
• HP 41xx switches
  
  
• Own ASN with BGP upstream connectivity
  
  

Requirements
 
Must-Have Skills
 

• Strong hands-on Linux system administration experience
  
  
• Ability to work independently and take full ownership of systems
  
  
• Experience with virtualization and VM management
  
  
• Solid troubleshooting and root-cause analysis skills
  
  
• Strong understanding of TCP/IP networking fundamentals
  
  
• Knowledge of SIP and RTP protocols (or ability to learn quickly)
  
  
• General networking knowledge (routing, switching basics)
  
  
• Excellent shell scripting (Bash) and/or Python skills
  
  
• Ability to automate routine operational tasks
  
  
• Fluent English for daily communication and video calls
  
  

Nice-to-Have
 

• Practical VoIP/SIP experience (Asterisk, Kamailio, SBCs)
  
  
• DevOps and automation tools (Ansible, Docker, CI/CD pipelines)
  
  
• Experience modernizing legacy infrastructure
  
  
• Basic familiarity with FreeBSD
  
  
• Additional programming experience in any language
  
  

Working Style & Tools
 
This is a hands-on, terminal-focused infrastructure role. The environment is predominantly command-line driven and built on Linux and open-source telecom technologies.
 
You should be comfortable spending most of your day in terminal sessions, debugging live systems, and editing configuration files directly. If you’re not already fluent with common Linux and networking utilities, this role may not be the right fit.
 
Work Setup
 

• 100% remote
  
  
• Part-time: approximately 4 hours per day (flexible schedule, Monday–Friday)
  
  
• Freelance/contract engagement
  
  
• Monthly compensation: €1,000
  
  

How to Apply
 
Please send your CV to: jobs@lightupnet.de