Abstract
This review deals with the research of load control mechanisms in signaling networks that use three types of thresholds for congestion control. The main objective of this paper is toanalyze the congestion control mechanisms and mathematical models for SIP-servers. Thestudy is based on hysteresial techniques of flow control, which originally was developed forSignaling System 7. We propose general methods for describing hysteresis signaling flow control techniques. We study the current situation and problems of SIP built-in overloadcontrol mechanism, proposed by IETF. Our approaches to mathematical models constructionin the form of queuing systems with hysteresis control are presented.