Zusammenfassung
Ridiculed at first and dismissed as inferior, Voice over IP (VoIP) has quietly matured over the years. Both in the enterprise and the carrier domain, VoIP installations today successfully rival classical telephony technology and will continue to gradually replace it. The wholesale market for voice minutes carried over IP has grown into a billion dollar business, and even incumbent carriers are seriously considering or already starting to deploy Next Generation Networks (NGNs) based on IP. This development, combined with the emergence of open standards such as H.323 and particularly SIP (Session Initiation Protocol), has opened up the opportunity for new entrants to the previously highly proprietary telephony equipment market. Vendors (such as Cisco with their VOCAL project) have recognized Linux and the Open Source model as a means of efficient and quality product development.
While the technical shift from classical TDM (time division multiplexing) to packet-based IP technology is a reality, it does not yet touch upon the established telco business model of call establishment and sale of voice minutes. Even with carrier backbones and enterprise PBXs being IP-based the local telco that operates the last mile still "owns the customer" and determines what services can be used. At the same time, however, business and residential broadband Internet access via DSL, cable or comparable technologies is becoming increasingly available in many markets worldwide, which has given a push to new applications such as file sharing networks. Access is typically charged by traffic volume (or customers pay a flat monthly fee). With an always-on IP access it is an obvious concept to use it for voice telephony as well.
Companies like Vonage in the US have turned that idea into a service offering, trying to merely take over the role of the traditional telco, still selling the same telephony minutes products. Over time however, voice telephony, which is a rather low-bandwidth application, is bound to become a commodity service to broadband users, and consumers will be less and less willing to be charged premium prices by the minute.
This presentation investigates different conceivable technological and business scenarios and the role open standards and Open Source implementations could play. Vendors of new gaming devices such as Microsoft with their X-Box are already starting to bundle centralized voice services as part of their Internet-based entertainment packages. Goverments are considering additional regulatory framework that might effectively preserve the existing telephony service model, albeit with probably some different players. On the other hand, open protocols such as SIP enable every IP device on the Internet to establish on its own a voice session to any other SIP user. User reachablity is achieved with the help of the proven, scalable, existing DNS (domain name service) system, on the long term doing away with need for classical telephone numbers and thus telephony switch operators, ultimately reducing the local telcos' role to that of last-mile Internet access providers. Such a scenario opens up the potential for voice telephony as a real peer-to-peer application. Success depends on the availability of suitable easy-to-use end-user telephony implementations and on how well issues such as Quality of Service (QoS), security and caller authentification can be addressed. Just as with the rise of electronic mail and later Web services, Open Source could play a crucial role here.
ﾜber den Autor
Georg Schwarz has experience with Open Source software and Linux for over 10 years. Since 2001, he is working as a consultant at Detecon's Technology Strategy practice. His scope of interest includes carrier IP backbones, Internet services, and Voice over IP. Georg holds a PhD in theoretical physics from Berlin University of Technology.
