A Session Initiation Protocol (SIP) proxy server including a multi-core central processing unit (CPU) is presented. The multi-core CPU includes a receiving core dedicated to pre-SIP message processing. The pre-SIP message processing may include message retrieval, header and payload parsing, and Call-ID hashing. The Call-ID hashing is used to determine a post-SIP processing core designated to process messages between particular user pair. The pre-SIP and post-SIP configuration allows for the use of multiple processing cores to utilize a single control plane, thereby providing an accurate topology of the network for each processing core.