Definition of Discarded VoIP Packet

Voice-over IP packets can be lost for several reasons.

A packet is a group of bits that together represent some real-world item. In a VoIP system, sounds are translated into groups of bits that are placed into packets for delivery to the remote end. Packets for any IP connection can be lost for any number of reasons. For data connections, lost packets must be retransmitted. For voice services, packets must arrive on time. Retransmitting packets that are lost would take too much time.

Lost Packets

Congestion can lead to packet loss.

Packets are lost in the network for two reasons. The main cause of packet loss is congestion. If a packet arrives at a router and the router buffers are full, the packet is discarded. Frames are used to transmit packets across any individual link. On any transmission link, one of the bits could change during transmission. This is a bit error. If a bit error is detected in a frame carrying the packet, it is discarded.

Delayed Packets

Voice is played out at a constant rate.

Voice services play a real-time sound made up of the data in packets sent from the other end of the circuit. If the data arrives too late, the time for playing that sound has already passed, so the packet is discarded.

Recovery

Sound must be generated even if the data is late.

When a packet is lost, the receiving end has to play some sound in place of the missing data. Usually the sound played is just the last sound played, but at reduced volume. If a large number of packets is lost in a row, the sound will fade away.