voopIX: Building free VoIP infrastructure for Academic, Science and Educational Institutions in Croatia entirely based on Open Source software Branko Radojević, Đivo Milić Hrvatska akademska i istraživačka mreža – CARNet, Zagreb, Hrvatska {Branko.Radojevic,Djivo.Milic}@CARNet.hr Abstract- One of many services that CARNet has in its network is called voopIX, which main goal is to provide free telephony service between CARNet member institutions by using Voice over IP standardized protocols and open source solutions. The main goal of this project is to interconnect existing legacy PBXes on institution premises by using VoIP gateways to transform traditional telephony standards (for example ISDN PRI connections) to VoIP. VoopIX project is entirely built and maintained by CARNets employees. At this time our reports show that, even in this early stage, we can terminate around 4% of all calls from institutions that are now using our system. We predict that this will grow to 10-15% of all calls and that will cut costs for about 2.000.000 EUR yearly in Croatia. I. INTRODUCTION CARNet, as a Croatian NREN (National Research and Educational Network), builds and maintains a well established high-speed IP network that for years was reserved for academic and science institutions in Croatia with approximately 300 connections. In 2004 network was considerably expanded to reach other educational (primary and secondary schools) and currently there are more than 3000 active connection points. CARNet is one of few NRENs in Europe that doesn’t provide only connectivity to GÉANT and commodity Internet, but also provides number of services on top of the fast network infrastructure, ranging from videoconferencing to hosting several centralized services in CARNet data centers. One of many services that are run on CARNets network is called voopIX, which main goal is to provide free telephony service between more than 3000 CARNet member institutions, but also to encourage movement from legacy PBX (Private Branch Exchange) solutions to modern VoIP based solutions on top of which new services and possibilities could be implemented. The starting idea of this project is to interconnect existing PBXes on institution premises by using VoIP gateways to transform traditional telephony standards (for example ISDN PRI connections) to VoIP, and then to transfer data across CARNets IP network. VoopIX project was designed, built and it is currently maintained by CARNets employees. It is considered to be the biggest VoIP implementation based on Open Source in Croatia [1]. Since the project is in production for more than three years now, and was preceded by additional two years of testing, and has proved to be an excellent solution in our environment, new possibilities and additional services that are explored now that can be offered to member institutions. II. CHALLENGES OF BUILDING NATIONAL VOIP NETWORK INFRASTRUCTURE This project is a kind of evolutionary one. It all started some four years ago with just two institutions with seven locations trying to establish VoIP interconnectivity. Since this initial solution proved to be technically easy to implement and the quality was excellent, it was expanded to other member institutions. Fig 1. Logical full-mesh of the voopIX network with two institutions connected to two neighboring core nodes for redundancy. VoopIX core network can run without a single core server without interruption.