From the website.

OpenSER is a project spawned from FhG FOKUS SIP Express Router (SER). The reason for this new venture is the lack of progressing and contributions to the SER project from the other SER team members as well as the reticence to new contributions from project's community members. We want to accelerate the integration of public contributions to the SER project.

OpenSER promotes a new management policy (OPEN) -for new code acceptance and code-through propagation- and development approach -design and architecture. We have decided to bring more dynamics into SIP world by creating this new project that can benefit of TLS and so many other contributions. We welcome your contributions to the success of this project.

The project is managed by three of SER developers: Bogdan-Andrei Iancu (core developer of SER), Daniel-Constantin Mierla (core developer of SER) and Elena-Ramona Modroiu (main contributor of SER). You all like SER so we will do our best to maintain our exiting work and help the users of our solutions. We will therefore maintain close contacts with our former colleagues and SER project.

The project is leaded by OpenSER Management Board and its history is summarized here.