Packet loss

When the system loses RTP packets in a network, the system also loses the portion of the audio stream within that packet. Most VoIP systems and devices play silence for that lost portion of the audio stream. The loss of RTP packets in a network can have various causes:

• Packet degradation - If a network node cannot read the information in the IP packet containing the RTP packet, the node discards the packet. This degradation could be the result of interference along the transmission medium, insufficient quality of the transmission medium, overextension of the transmission medium, or intermittent power problems in the transmitter.

• Long delays of single packets - Problems in a network can cause a delay of individual packets so that the system receives them long after subsequent packets. In most VoIP solutions, the system discards these delayed packets because their position in the audio stream passed and the system replaced them with either silence or sound extrapolated from the surrounding packets. Overburdened network switches, improper Quality of Service (QoS) settings in a network node, or a lack of QoS in a network node can cause delays in individual packet transmission.