1. A method for processing a protocol message, the method comprising: in a receiving core of a multi-core processor, the receiving core configured to perform pre-SIP processing of protocol messages: given a plurality of different media sessions between users, for each of the media sessions, analyzing a protocol message sent to the receiving core in order to determine an associated call identifier, wherein the call identifier uniquely identifies protocol messages, including the protocol message being analyzed, associated with one of the media sessions, wherein for each media session, all corresponding protocol messages are identified by a single respective call identifier; hashing the call identifier with a hash function at the receiving core in order to determine a processing core from a plurality of processing cores in the multi-core processor, the processing cores configured to perform post-SIP processing of protocol messages; and directing the protocol message analyzed to the processing core determined, wherein for each media session, all the corresponding protocol messages are directed to a single respective processing core of the plurality of processing cores in the multi-core processor.