A call processing system and method based on an answer mode of a Push-to-Talk over Cellular (PoC) user are provided. A data format is defined, which inserts an indicator indicating a manual answer override into a payload of a Real-time Transport Control Protocol (RTCP) in a format of a new data field. When a PoC communication requester instructs the MAO to perform PoC communication regardless of an answer mode of a reception side PoC user, an auto-answer mode is immediately executed without any procedure of checking the instruction. In addition, when the reception side PoC user establishes an early session with a home PoC server in its own PoC terminal, the call processing can be performed at a quicker speed.