Call set-up time modeling for SIP-based stateless and stateful calls in next generation networks

This paper examines the call set-up delay (CSD), a performance parameter that may be used in specifying, measuring, and comparing the speed of call set-up processing in networks that employ the session initiation protocol (SIP), in establishing and terminating media sessions (calls) between users. One of the most important standardized technologies that use SIP in this way is the IP multimedia subsystem (IMS) which supports the provision of SIP-based multimedia services to next generation networks (NGN) terminals. The approach taken is, initially, to present some basic concepts for understanding and discussing call set-up in the context of SIP-based networks. Following this, we present some queuing models to simulate and calculate the call set-up delay in various scenarios (i.e., stateless, stateful, single domain and multi-domain scenarios). The proposed models can be used to examine the call set-up delay in other networks and scenarios considering the role of other network elements in the call flows.