Personal website of

Prof. Dr.-Ing. habil. Falko Dressler


Voice over IP in the German research network


  • Regional Computing Center Erlangen, University of Erlangen-Nuremberg


  • Falko Dressler (coordination)
  • Peter Holleczek
  • Ursula Hilgers


  • internal project

Project Time

  • 01.01.2000 - 31.12.2003


In 2000 we started to deploy a first voice over IP network at the University of Erlangen-Nuremberg. The primary goal of this testbed was to allow studies of the available VoIP components. The research focus was to measure the required transmission quality in the network as well as to test the interoperability of the different VoIP devices.
We installed a Cisco Callmanager (starting with version 2.4, currently we use 3.2) and a number of Cisco hard-phones and some hard-phones from Siemens. Additionally, software based telephony applications from Microsoft and from Cisco have been deployed.
It became obvious that the telephony applications can be used over the standard IP campus network and even over the German research network. Nevertheless, there is no guaranteed transmission quality and therefore no benefit over the standard telephone system. If QoS mechanisms are deployed in the network such as prioritization of the VoIP traffic, the quality of the voice over IP applications is comparable to the standard telephone system.
As the result of some talks in Dresden, a first cooperation was initiated between the University of Erlangen-Nuremberg (Falko Dressler) and the Saarland University (Edgar Scherer). A working group was established in 2001. Until the end of 2002, about 20 universities, research instituts, and leading manufacturers of VoIP hardware joined the group.

In the end of 2002, the focus of the working group shifted from a research project to questions about the operating of single VoIP clouds.

Selected Publications

  • Falko Dressler, Ursula Hilgers and Peter Holleczek, "Voice over IP in the German Research Network: Challenges and Solutions," Proceedings of 2nd IASTED International Conference on Communications, Internet, and Information Technology (CIIT 2003), Scottsdale, AZ, November 2003, pp. 710–714. [BibTeX, PDF, More details]
  • Falko Dressler, "Advantages of VoIP in the German Research Network," Proceedings of IEEE International Conference on High Speed Networks and Multimedia Communications (HSNMC 2002), Jeju City, South Korea, July 2002, pp. 56–60. [DOI, BibTeX, PDF, More details]
  • Ursula Hilgers and Falko Dressler, "Echtzeit-Datenverkehr über IP-basierte Datennetze," Proceedings of Echtzeitkommunikation und Ethernet/Internet: Fachtagung der GI-Fachgruppe 4.4.2 Echtzeitprogrammierung (PEARL 2001), Boppard, Germany, November 2001, pp. 29–39. [BibTeX, PDF, More details]
  • Falko Dressler, Ursula Hilgers and Peter Holleczek, "Voice over IP in Weitverkehrsnetzen?," Proceedings of Anwendungs- und System-Management im Zeichen von Multimedia und E-Business: Fachtagung der GI-Fachgruppe 3.4 Betrieb von Informations- und Kommunikationssystemen (BIK 2001), Tübingen, Germany, April 2001. [BibTeX, PDF, More details]
Last modified: 2023-10-07