Bandwidth consumption depends on which codec is used for conversation. Normal conversation includes a lot of silence which means that full bandwidth is not used all the time. Also, each codec stream can result in a larger bandwidth due to IP and UDP headers and overheads. The following data displays the bandwidth usage with and without the UDP/IP headers:


Codec      Bit rate      Total Used Bandwidth
G.711      64 Kbps       87.2 Kbps
G.729      8 Kbps        31.2 Kbps
G.723.1    6.4 Kbps      21.9 Kbps
G.723.1    5.3 Kbps      20.8 Kbps
G.726      32 Kbps       55.2 Kbps
G.726      24 Kbps       47.2 Kbps
G.728      16 Kbps       31.5 Kbps
iLBC       15 Kbps       27.7 Kbps