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# Backend PHP PBX Developer

- **Company:** Mixvoip's Saga
- **Location:** Luxemburg, Belgium
- **Contract:** Internship / Graduate position
- **Skills:** PHP (Programming Language), Automatic Call Distributor, Application Programming Interfaces (APIs), Artificial Intelligence, VoIP, Databases, Cron, Software Debugging, Linux, Network Address Translation, Domain Name System (DNS), Internet Protocol, JSON, Routing, Open Source Technology, Wireless Networks, Firewalls (Computer Science), Backend, Twig (templating), Kamailio, Docker
- **Published:** October 27, 2026
- **Apply:** https://www.mixvoip.com/company/career/pbx-backend-dev/

## About the Role

* Knowledge of PHP or another backend programming language
 * Comfort working in a Linux environment
 * Understanding of APIs, databases, JSON, and structured data
 * Interest in VoIP, telephony, networking, or infrastructure
 * A methodical approach to debugging and problem-solving
 * Clear communication and a collaborative attitude
 * Willingness to learn unfamiliar systems
 * Ability to work regularly from our Luxembourg office

For junior candidates, internships, apprenticeships, school projects, open-source work, home labs, and personal projects all count.
For experienced candidates, we value ownership, system design, production troubleshooting, performance awareness, and the ability to improve existing systems.

Useful experience
Previous experience with any of the following is helpful, but not required:

 * SIP
 * Asterisk
 * PBX systems
 * Call routing and dial plans
 * VoIP device provisioning
 * Twig configuration templates
 * Docker
 * Cron jobs and background workers
 * IP networking, routing, DNS, NAT, and firewalls
 * Telecom vendor APIs
 * Monitoring and troubleshooting production systems, * Experience with SIP, Asterisk, FreePBX, Kamailio, 3CX, or similar systems
 * Strong PHP and Linux experience
 * Experience running production backend or infrastructure systems
 * Personal projects involving networking, telephony, automation, or self-hosting
 * Experience with Docker, servers, routers, or home labs
 * Strong troubleshooting and documentation habits
 * Practical use of AI coding tools in your daily workflow
 * Genuine curiosity about how phone calls are routed and connected

## Description

You will join our PBX development team and work on the systems that control call routing, device provisioning, configuration generation, and telephony automation.
This is not a traditional web development role. There is no frontend, UI, or CSS work. Most of your work will involve backend services, CLI tools, scheduled jobs, APIs, configuration files, and direct interaction with our VoIP infrastructure.
You will use PHP and Linux to develop and maintain features for our PBX platform.
Depending on your experience, you may start with smaller, well-defined tasks and grow into more complex responsibilities, or you may take ownership of larger areas from the beginning.
This role requires regular on-site presence at our office in Luxembourg and is not a remote position.

What you will do

 * Develop and maintain features for our cloud PBX platform
 * Implement call-routing rules and telephony configuration
 * Generate PBX and device configuration files
 * Automate the provisioning of Yealink, Gigaset, and Grandstream devices
 * Integrate internal systems and external telecom APIs
 * Build CLI tools, background workers, and scheduled jobs
 * Maintain configuration templates using Twig
 * Investigate call-flow, provisioning, and integration issues
 * Work with logs to troubleshoot telephony problems
 * Document PBX behaviour, code, and operational workflows
 * Improve the reliability and maintainability of the platform, You will receive guidance, learn how the platform works, and begin with manageable tasks such as:
 * Updating configuration templates
 * Fixing provisioning issues
 * Improving existing PHP scripts
 * Investigating logs
 * Making small API changes
 * Testing routing rules
 * Writing documentation

As your knowledge grows, you will gradually take ownership of larger PBX features and automation projects.

If you are more experienced
You may take ownership of larger technical areas, including:

 * Designing new PBX capabilities
 * Improving platform architecture
 * Leading complex integrations
 * Strengthening reliability and observability
 * Reviewing code and technical approaches
 * Mentoring less experienced developers
 * Helping define engineering standards and long-term improvements