QoS of ISDN networks versus QoS of IP networks

The sphere of communications is changing rapidly. Two different 'worlds' exist-telecommunications and computer networks. These worlds are converging, each of them pushing its technologies. The integrated services digital network (ISDN) (most matured telecommunications network) is based on circuit-switching transfer mode. It offers services with guaranteed quality of service (QoS). Internet protocol networks (most common data networks) are based on packet-switching transfer mode. At present, it does not explicitly guarantee QoS parameters. IP networks are capable of transferring services that are similar to ISDN network services. QoS parameters are crucial for the success of communication services. The meaning of the term QoS in ISDN and IP networks is significantly different. At the end of this paper QoS parameters of ISDN and IP networks are compared. IP networks are being innovated; further improvements of their QoS parameters are expected.