We have come to measure quality of packetized voice service by the equivalent service offered by the switched digital network, sometimes called G.711 (Ref. 1) service. The user expects a quality of service (QoS) as good as he/she would get on a PSTN dial-up connection.
To achieve this goal, VoIP designers were faced with the following degradations:
- Mouth-to-ear delay;
- Impact of erred frames (packets);
- Lost frames (packets);
- Variation of packet arrival time, jitter buffering;
- Prioritizing VoIP traffic over regular Internet and data services;
- Talker echo;
- Sufficient bit rate capacity on interconnecting transmission media;
- Voice coding algorithm standardization;
- Optimized standard packet payload size;
- Packet overhead; and
- Silence suppression.