Publications & Reports - Document Abstract
Voice-over-IP (VoIP) is currently one of the most commonly used communication options and Session Initiation Protocol (SIP) is most often used for VoIP deployment. However, there is not a lot of general knowledge about typical SIP traffic and research in this area largely works with various assumptions. To address this deficiency, we present a thorough study of traffic of a real, free and publicly open SIP server. The findings reveal, among others, a surprisingly high overhead of SIP due to connection maintenance through Network Address Translation (NAT) nodes, differences from typical Web server Zipf-law patterns and various unexpected creative uses of SIP servers.