IP TELEPHONE SYSTEM, LINE EXCHANGE DEVICE, AND PROCESSING METHOD

PROBLEM TO BE SOLVED: To excellently reproduce voice in a reception side IP telephone terminal even when a part of a voice packet transmitted from a transmission side IP telephone terminal is not received by a line exchange device and the packet is not transmitted to the reception side IP telephone terminal when communication during a call is held or the holding state is released. SOLUTION: During the call before holding, the voice packet transmitted from the IP telephone terminal 31 is transmitted without rewriting a sequence number. In the holding state, a holding sound packet is transmitted by successively setting the last sequence number in the voice packet which is transmitted before holding or the subsequent numbers as sequence numbers. In a call state after holding release, the voice packet transmitted from the IP telephone terminal 31 is transmitted after rewriting the sequence number from Nx to (Nx+ΔN). The number ΔN is the total number of holding sound packets transmitted during the holding. COPYRIGHT: (C)2010,JPO&INPIT