When we go to talk on the phone through a line with IP voice , we want to make sure not to consume too much bandwidth to our call. For that we have to look at a series of measures to calculate and optimize the bandwidth, since the sending of audio data can lead to line collapses and other inconveniences.
1. Choose voice codecs well
Once it made the signage (off - hook telephone, dial, phone sound connection between two phones), we are producing audio data raw to be processed before being sent over the network. These data are coded through a codec. There are different types of codec , and it is important to choose one that consumes little bandwidth.
What kind of codecs are there? Although there are many that we do not include here, let's look at some of the best known:
- G711: is one of the most used and voice quality is excellent, but consumes a lot of bandwidth
- G729: undoubtedly the best in the low number of delays, low-bandwidth and voice quality.
- G722: audio quality is average, but the resources it consumes are very high
- G723: consumes little bandwidth, but unfortunately the voice quality is very low
- GSM: good audio quality, although consumption of bandwidth is higher or lower
The transmission intervals of voice packets also influence the consumption of bandwidth: as we increase the number of kbps, more latency (delay) in the transmission of voice, but consumes less bandwidth (and vice versa).
2. Measure the packetization of voice
In addition to choosing a suitable codec, we must also understand that this will not be the end result of consumption of bandwidth . The encoded information not be transmitted directly, but through different data packets transmitted by different protocols. Each of these packages consumes bandwidth.
RTP stands for Real-time Transport Protocol. It is the protocol that is used in video conferences for the transmission of audio and video in real time. VOIP calls work thanks to this protocol, but it also consumes (4.8 kbps)
UDP: literally it means User Datagram Protocol and is a transport system datagrams (IP data packets). It is used to send data over a network without a connection being established previously. Although the protocol is not secure and datagrams do not arrive in an orderly way, it is used for video and audio transmission because it guarantees the speed above the arrival of all bytes to the destination point. Consumes 3.2 kbps.
IP: is the Internet protocol, through which the voice data is transmitted over a computer network. Consumes 8 kbps.
Ethernet IP data package through the Ethernet protocol, which consumes around 15.2 kbps.
As you can see, there are several parameters that influence the bandwidth consumption of our telecommunications system IP voice in the company . If we want our VoIP system to go fast enough, we must consider these aspects and understand, the more quality of voice transmission we want and the less latency, the more bandwidth it requires.
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