Session initiation protocol (SIP) is a widely used standard protocol for multimedia applications and IP multimedia subsystems. Internet protocol multimedia subsystem was introduced by the 3GGP signaling foundation as part of a set of next generation network architectures. Despite having useful practical features, SIP does not have suitable mechanisms to handle overload. This challenge creates a sharp drop in quality of service for next generation network users. Because a distributed SIP network is a complex system composed of subsystems interacting with one another, multiagent system is an appropriate method to model network interactions and to solve overload in SIP networks. In this paper, holonic organization is applied to reduce the multiagent system complexity in modeling a large SIP network. Holonic organization is a hierarchical structure in which each holon covers a geographical area of the SIP network at the first level. At the second level, upper‐level holons control the first‐level holons, and so on. Overload control is achieved by communication and the exchange of knowledge between the intelligent holons. Experimental results show that the proposed method prevents overload in the SIP network. The method also increases total throughput, reduces delay, and considers fairness in the SIP network.