Senior AI / Machine Learning Engineer (Full-Stack)

About sipgate

We are a successful, owner-managed and self-financed SaaS company with a beautiful campus in Düsseldorf's media harbour. Since 2004, we have been building telephony solutions with around 250 colleagues, working cross-functionally, self-organised, always fairly and on equal footing.

sipgate is a German company based in Düsseldorf with currently 260 employees. sipgate was the first German VoIP provider in 2004 and develops telecommunications products that should do better than established ones. Today, sipgate is a VoIP and mobile provider with private and business offerings. sipgate basic replaces the landline connection at home, simquadrat offers mobile services with numerous innovations and new features for demanding private customers. With sipgate team we offer a cloud telephone system with mobile integration for companies, and sipgate trunking enables VoIP telephone systems to connect to the telephone network.

About the role

As a Senior AI / Machine Learning Engineer with a full-stack background, you will develop systems at sipgate where machine learning and modern AI are a central part of real product features.

You bring proven experience from productive AI/ML systems and use this knowledge to implement solutions not only, but also validate them reliably and at scale.

You work independently, make well-founded technical decisions and contribute ideas that sustainably advance your team and our products.

Your day-to-day at sipgate

You work in a Research & Development team where not every day looks the same.

This means:

• You independently identify topics with potential
• You actively drive new ideas and technologies forward
• You move between exploration, prototyping and productive implementation

We are not looking for a person for clearly defined tickets, but someone who brings design willingness, curiosity and ownership.

What you bring

AI & Machine Learning (focus)

• Conception, construction and operation of AI/ML systems in productive deployment
• Work on conversational AI as well as voice and audio systems (speech-to-text, text-to-speech)
• Integration and orchestration of Large Language Models in real use cases
• Development of scalable AI workflows (e.g. multi-agent systems)
• Selection, evaluation and further development of models and approaches
• Development and use of evaluation and benchmarking methods
• Optimisation of existing systems based on measurable metrics (e.g. quality, latency, costs)

Full-Stack & Backend Engineering

• Development and operation of web and API servers with TypeScript (e.g. NestJS)
• Construction and maintenance of databases (e.g. PostgreSQL, vector-based systems)
• Development of scalable SaaS backends
• Collaboration on web frontends (e.g. React)
• Responsibility for operations, deployments and monitoring

Cloud & Infrastructure

• Experience operating AI/ML systems in cloud environments
• Understanding of scaling, deployment and monitoring of distributed systems
• Use of cloud services for data processing, model operation or integrations

Requirements

• Fluent German (minimum C1)
• Resident in Germany
• Willing to work with us in Düsseldorf at least 1x per month

How sipgate works

We are agile from head to toe and not just on paper.

We have flat hierarchies and peer responsibility is our creed – this means: taking responsibility, making your own decisions and looking out for each other are highly valued.

We have a transparent salary model and no individual salary negotiations.

Sustainability is important to us – our fleet consists only of electric cars, private cars charge for free during working hours, we source our electricity from solar panels, we eat organic and regional and try to avoid waste.

We firmly believe in our 'come as you are' principle and are on a journey to make sipgate so inclusive that we warmly welcome people of all genders, ethnic backgrounds, body shapes and social backgrounds to become part of our team.

Final note

If you feel you are the right person for us, even if you cannot tick off every point in the job description, please get in touch. Let's chat and find out if we're still a good fit for each other!