2002 - cesnet

H.323 WorldSIP PhoneMS Messengerand Linux PhoneCESNETH.323 PhoneSH SIP ProxySERCESNETSIP PhoneCiscoMS Messengerand Linux PhoneCESNETH.323 GKKerio, CiscoSIP323GWKerio, SiemensAliatel GWCisco GWRadiusPSTNPBX ČVUT PBX Phone... and all other GWs and PBXs... and other trustedSIP ServersSIP WorldRadius or MySQLCESNETSIP ProxySERGW routing, AccountingIPTAAccounting serverFigure 8.7: Configuration of IP telephony with SIP signallingWe carried out a survey among the existing products, which allow for certaininteroperability of H.323 and SIP protocols, and decided to check the possibledeployment of three translating gateways by Kerio, Siemens and DarmstadtUniversity.8.6.1 KerioThe first tested gateway was produced by Kerio. This version runs under Linux.In CESNET, we use a Kerio Gatekeeper for Windows 2000 with very good results.One of the disadvantages is the need to use a Windows-based management software.No management console has been developed for Linux so far.The gateway was originally designed to the translate SIP signalling into PSTN,usually through ISDN. However, it was later extended with the translation intothe H.323 signalling. Only a test version is available, but thanks to very goodcollaboration with the developing team, we managed to correct all problemsidentified so far and the gateway is fully functional. On the other hand, the configurationof the gateway is rather complicated. In addition, the software operatesas a media gateway, even though it is not necessary.This means that voice data are not transmitted directly between end stations,but pass through a gateway, which produces an unwanted delay. However, test-High-speed National Research Network and its New Applications 2002117