The present invention provides a system, method and a memory product storing a computer program for recording call details that allows inexpensive recording of voice data of a phone call on the IP phone system, while easily maintaining high sound quality of the call. A CDR system is provided with a transferring means for transferring the voice packet to a receiving side IP phone upon receipt thereof from the calling side IP phone and records the voice packet upon receipt thereof from the calling side phone and the receiving side phone in a recording means, and a call controller acquires a condition for deciding whether or not to record the voice packet representing the call between the phones; and transmits information relating to a destination with which a call with the transferring means is to be established, in case of having decided to record the voice packet representing the call.