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Voice Over IP Service

Are you interested in associating your Institute with the Voice Over IP service of the GUnet network?

Service Description

imgThe Voice Over IP service is one of the main GUnet Academic Network activities. Its aim is to provide telephone services free of charge the Academic Institute end-users. In that way, the ability of the data network to transfer voice packets is exploited, while cooperation and communication amongst members of the Academic community is greatly encouraged. Finally, Academic Institute telecommunication fees are restricted.

The service is based on the H.323 international model which designates a series of network components and protocols for the transfer of voice, video and data in real time. The H.323 network backbone is implemented on a central gatekeeper (national gatekeeper), which supports national and international prefixes of the Academic Institutes and GRnet S.A. In parallel, high service availability is assured through a secondary central gatekeeper, whose goal is to accept Institute gatekeeper requests, when the primary directory gatekeeper is set out of service or is inaccessible.

Each Academic Institute needs to own the necessary equipment in order to connect to the GUnet Voice Over IP service. It consists of:

  • an H.323 Gatekeeper
  • one or more Η.323 gateways
  • the PBX that serves the traditional and/or the IP Institute telephony
  • traditional or IP phones
  • H.323 terminal stations, namely PCs with Netmeeting, Openphone etc. software and the appropriate equipment (e.g. microphone, headphones)

The gatekeeper of each Institute communicates with the central gatekeeper which serves the gunet.gr and grnet.gr zones.

The service is provided in cooperation with the GRnet.

GUnet is responsible for the Institutes interconnection with the Voice Over IP service, numbering maintenance, technical support, service availability, as well as providing a connection towards residential telephony in Athens for the Institutes that are interested in that kind of service.

GRnet is responsible for routing the Global Dialling Scheme (GDS) user calls, as well as for security and quality of the VoIP service that is supplied to all research, academic and educational community of the GRnet.

Whom the service addresses

Initially, the service is targeted to the Academic Institutes Network Operations Centers. However, the goal of the service is to be widely used by all end users of the Academic Institutes.

How to apply

Please follow this link in order to apply for the affiliation of your Institute to GUnet Voice Over IP service.

Technical potential


Users of the Academic Institutes Voice Over IP service are able to make calls either by traditional or IP phones, or H.323 terminals, namely PCs with Microsoft Netmeeting, Openphone, etc. These devices also need to have the necessary equipment, namely a microphone and headphones or a set of speakers.

The GUnet VoIP service also provides the opportunity of making phone calls towards international research, academic and educational community that participate in the GDS network.

The adopted numbering system is according to the E.164 “00-country code-area code-number” international form. The national gatekeeper serves all calls with a “0030” prefix and forwards the calls of Greek Academic Institutes’ gatekeepers towards international GDS gatekeepers, which recognize all the “national” ones.

For more technical information you can email us at: helpdeskgunet.gr