QoS of ISDN networks versus QoS of IP networks

The sphere of communications is changing rapidly. Two different 'worlds' ex ist-telecommunications and computer networks. These worlds are converging, each of them pushing its technologies. The integrated services digital netw ork (ISDN) (most matured telecommunications network) is based on circuit-sw itching transfer mode. It offers services with guaranteed quality of servic e (QoS). Internet protocol networks (most common data networks) are based o n packet-switching transfer mode. At present, it does not explicitly guaran tee QoS parameters. IP networks are capable of transferring services that a re similar to ISDN network services. QoS parameters are crucial for the suc cess of communication services. The meaning of the term QoS in ISDN and IP networks is significantly different. At the end of this paper QoS parameter s of ISDN and IP networks are compared. IP networks are being innovated; fu rther improvements of their QoS parameters are expected.