Sip signalling delay in 3GPP

The Session Initiation Protocol (SIP) will be used as the signalling protocol in the IP Multimedia Subsystem (IMS) of 3rd Generation Partnership Project (3GPP) UNITS networks. This paper discusses the delay as a relevant signalling Quality of Service (QoS) parameter. It outlines possible problems concerning the delay for signalling messages and provides empirical estimates for expected delays using existing UDP delay trace data. Simulation results verify the estimates. It is concluded that further study is required to ensure satisfactory QoS, in particular if 3GPP IM Subsystem is to provide equivalent telephony services.