Call Setup Delay Analysis of H.323 and SIP

Abstract: IP Telephony is a technology which uses internet and signalling protocols like H.323 and SIP to setup and transfer voice signals from one destination to another. These protocols use various encoding schemes to transmit voice signals over the digital technology. The success of IP Telephony is the cost and time effectiveness; hence we studied on the call setup delay of these two signaling protocols H.323 and SIP. H.323 uses TCP and SIP uses UDP as transport protocols to set up a call. They have different scopes that distinguish them. The signalling protocols H.323 and SIP call setup delays are observed and studied successfully between the traditional telephones and IP telephones. The call setup delay for H.323 is analysed experimentally in the Cisco environment by establishing calls at various loads such as null load, medium load and heavy load. Due to practical difficulties the SIP call setup delay is studied only literally. The parameters that we considered for our experiments are the average call setup delay, bandwidth and different traffic loads. Finally, the results of both H.323 and SIP are compared with each other to find out the best signalling protocol. The comparison is done according to the call setup delay and other factors like complexity, compatibility, reliability and bandwidth utilization.