Case Study: Fraunhofer FOKUS achieves accelerated IMS adoption and a scalable multi-million-user HSS with MySQL

IMS Adoption Fueled by the Open IMS Core Project and MySQL

Fraunhofer Institute FOKUS developed the Open IMS Core project to accelerate adoption of IP Multimedia Subsystem (IMS) technology and create a developer community and R&D test-bed for next-generation telecom networks. The challenge was to provide a realistic, standards-compliant IMS core (CSCFs and HSS) that supports interoperability and prototyping while remaining affordable and scalable for operators, vendors and university projects.

The team built an open-source IMS core using SIP Express Router (SER) modules and a MySQL-backed Home Subscriber Server (FHoSS) with Java/Tomcat application logic, deployable on off-the-shelf hardware. The solution delivered carrier-grade behavior—supporting a million subscribers on a single workstation and handling hundreds of registrations per second with sub-30ms latency—has been adopted by leading operators and vendors, reduced test-bed costs, and enabled widespread prototyping, interoperability testing and community growth.

Fraunhofer FOKUS

Peter Weik

Senior Researcher