In this paper, we develop a mathematical model of a load control mechanism for SIP server signaling networks based on a hysteretic technique. We investigate loss-based overload control, as proposed in recent IETF documents. The queuing model takes into account three types of system state - normal load, overload, and discard. The hysteretic control is made possible by introducing two thresholds, L and H, in the buffer of total size R. We constructed an analytical model of SIP server with K-state MMPP flow, input flow and bi-level hysteretic overload control mechanism to investigate the performance indicators of a SIP server in the case of bursty input message flow. Algorithms for computation the key performance parameters of the system were introduced. A numerical example illustrating the control mechanism that minimizes the return time from overloading states satisfying the throttling and mean control cycle time constraints is also presented. © 2014 IEEE.