There is provided a system, method and computer program product for managing network communications to a Session Initiation Protocol (SIP) server. In the system, a packet limiter receives packets relating to SIP messages from a network and selectively forwards said packets for initial SIP processing. A work scheduler then accesses the result of the initial SIP processing and determines whether to proceed with further SIP processing based on a level of system activity. If a level of system activity is such that the system should proceed with further SIP processing, then further SIP processing may be scheduled. Initial SIP processing may involve one or more of parsing, request handling and response handling. Further SIP processing may involve one or more of initiating a new dialog, processing SIP messages relating to an existing dialog and processing messages that do not require a dialog.