Packetization Latency

Digital Signal Processing (DSP) hardware takes the spoken word and prepares it for transmission via a IP network by packetizing and prioritizing the data. The process is called “vocoding”. Vocoding processes voice in batches of data at a time and places it in baskets that are of fixed size. Latency occurs in DSP when vocoding waits on packets to fill the basket. The larger the basket, the more efficient the call, but with a higher danger of latency. G.711 protocol uses a basket size of 120 bytes, which is considered uncompressed VoIP. This is in coincidentally equal to 64 kbps of data, the size of an analog POTS phone line. G.729a, the most popular compressed basket, is 10 bytes and uses 8 Kbps of bandwidth. This is a latency efficient protocol.