http://www.cesnet.cz/english/project/iptelephony
CESNET IP telephony project started in 1999 with the goal to investigate possibilities of data and voice network convergence. CESNET operates Czech NREN. A lot of experience was acquired about optimal interconnection configurations of various telephony devices (PBXs with different interfaces, voice gateways, gatekeepers, IP phones, etc.). It turned out that most popular IP telephony service has been the least cost routing. Over the time 24 PBXs in universities and research institutes have been interconnected over Czech NREN with two gateways to PSTN. The network structure is illustrated in figure Figure A.1.
