Modelling and analysis of VoIP call centre server performance with impatient callers, re-service, service interruption and buffer search

The paper investigates a retrial queueing scenario in a voice over internet protocol (VoIP) call centre. A single server with two stage service process is considered with the initial phase being the obligatory phase of service and the additional phase being the selective phase of service. The incoming calls arrive in multiple voice packets in accordance with the Poisson process. The system focuses on the behaviour of the caller and the server. Caller behaviour comprises of the impatient callers and callers opting for re-service. Server behaviour comprises of buffer search and service interruption followed by the immediate repair process. After the repair completion, the server continues the service for the interrupted caller. The steady state equations are framed for the system and performance measures are derived using supplementary variable technique. Numerical analysis and cost analysis are presented to analyse the performance of the system.