This paper describes the approach and preliminary results from the research project EUX2010sec. The project works closely with Voice-over-IP (VoIP) companies and users. It aims at providing better security of open source VoIP installations. The work towards this goal is organized by gathering researchers and practitioners around several scientific activities that range from security modeling and verification up to testbed testing. The expected outcomes of the project are a solid scientific and practical understanding of the security options for setting up VoIP infrastructures, particular guidance on secure, typical setups of such infrastructures, The project’s special focus is on producing results relevant to the practitioners in the project, aiming at the stimulation of innovation and the provision of highest quality in open-source based VoIP products and services.