The following are the most common problems of using VoIP and simple ways to solve such problems.
Delay
Occurs more often on older computers when encoding audio — that is, when the sound of a voice is converted into a digital signal. Or during the transmission of data through the user's network. IP telephony features usually make it possible to neutralize the effects of a delay. But when it exceeds 250 ms, it begins to affect the quality of communication.
The main causes of network data latency
Accumulation delay or algorithmic delay - occurs during audio encoding. Its value is determined by the type of speech codec. - technologies for voice data compression. And it can range from 0.125 ms to milliseconds.
Processing latency - happens during encoding and data collection, broken down into packets, for transmission over a network. It is due to the processor and the algorithm used.
Network latency - caused by the physical medium and protocols that are used for voice transmission. In addition, it can cause incorrect operation of jitter buffers, which are discussed in the next section.
There are a number of problems with the delay. It affects not only call quality, but also speech clarity. The longer it is, the harder it is to talk because the interlocutors start to interrupt. It can also overlap echoes and voices.
Data loss
With errors in the package or delay, data may be lost, and not reaching the end user. This occurs during compression and/or transmission in IP telephony equipment. Most often the fault is overloaded network or unreliable connection. As a result, the signal is distorted.
The human ear perceives the loss of the package as a distortion of the tone of the interlocutor's voice and the loss of sound. According to nextiva reviews it can be noticed only if 10-15% of the data is lost. But these figures are highly dependent on the compression and decoding algorithms.
Echo
What is beautiful in the forest, in the case of IP telephony, is just a misfortune. Speech is about echo, which becomes noticeable with a delay of 10 ms and more. There are such types of echo in communication over the Internet:
Acoustic - occurs in the handset if the other person keeps it away from the head or turned on the speakerphone. It can also be caused by a poorly designed tube. In this case, the subscriber's microphone reflects back to the line the sounds coming from the headphone.
Hybrid - differs from acoustic in that it occurs at the transition points between some trunks. These are point-by-point connections between switches and devices on the network. For example, a hybrid echo occurs when a customer calls from an analog PBX to a digital one. Or digital PBX redirects the call to analog.
Occurs when data is delayed. Its reasons are similar to the reasons for the delay, which we described above.
To get rid of the acoustic echo, it is enough to make less volume in the device that broadcasts the sound. To combat its other species, an echo canceller is needed, which is also an echo canceller. This is a special scheme for eliminating echoes, which is built in by the manufacturers of the gateways into the device for transmitting/receiving audio.
In case they are similar, an echo canceller compares removes unnecessary data using a digital filter. But this technique works only if the delay does not exceed 30-200 ms.
To avoid this, you should start using wired devices instead of wireless ones. Try to identify the “culprit” of poor communication. See what equipment refuses to work for no reason. Turn it off and repeat the call to make sure that it is the cause of poor communication.
We hope that these simple recommendations will help you improve the quality of communication. In future articles about IP telephony, we will dig deeper and talk about network problems.