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XymphonyProgramming-BandwidthUsedInVoIPCallsInMinutes

The data used in VoIP applications differ according to the codec type and the package size of the codecs. For example, sending RTP Payload (voice packets) in 90 ms packet size and 30 ms packet size or using G729 codec instead of G723 codec affects data size.

Size of data used by codecs in one second, excluding header fields

• G711 codec 8000 Byte
• G729 codec 1000 Byte
• G723.1 (6.4Kbps) codec 800 Byte
• G723.1 (5.4Kbps) codec 667 Byte

When the headers are added to the above data size, the actual size can be calculated.

For example, when we look at a G723 RTP Payload package, this package has a 42-byte IP+UDP header and a 12-byte RTP header. If you are sending G723 RTP payload packets with a length of 90 ms, approximately 11 RTP packets will be sent every 1 second and (42+12)*11.11=600 bytes only headers take up space and since the G723 codec carries 800 bytes of data in 1 second, a total of 800+600=1400 Byte in 1 second. That is, 1.4 Kbytes of data are used, or 84 Kbytes of data are used in one minute (1400 * 60 = 84000).

If you send the RTP payload data size in 30 ms, approximately 33 RTP packets will be sent every 1 second (42+12)*33.33=1800 Byte headers take up space. Total data size in one second is 1800+800=2600 ie 2.6 Kbytes. 156 KBytes of data are used per minute (2600 * 60 = 156000)

The table below shows the data sizes used by different codecs at different RTP voice packet sizes per second.