Sometimes when we communicate on two different networks through voip devices such as IP phones, we may find that our speech probably is intermittent or we hear some acoustic echo. These make us feel a bad communication. That is because the quality of VoIP communication will be influenced by the network environment. We can test the network environment via the command ping.
For example, if we need register remotely to the sip server which is in the company but our device is in another network, so we can use the command ping to test how the network environment is. We consume that the IP address of the sip server is 220.127.116.11, a public IP, if we ping it, we will get some information as the picture shown below.
In this picture, we can see Packet Loss Rate, Network Delay and Network Jitter, from which we will know about the specific conditions of the network environment.
1. Packet Loss Rate.
In the picture, the packet loss rate is 6%, but to create a high quality VoIP communication, the Packet Loss Rate should be lower than 1%.Since the frequent voice packet loss will cause an intermittent speech. And the packet loss rate is lower, the higher quality communication will be.
2. Network One-way Delay.
The average network delay is 154ms in the picture, the maximum delay is 160ms, and the minimum delay is 150ms.
In accordance with the standard of ITU (International Telecommunication Unions), a high quality VoIP communication requires the network one-way delay is less than 150ms. When a one-way delay is larger than 250ms, both sides will feel obvious delay of the reaction which comes from the other side.
Therefore, the Network One-Way Delay should better be less than 200ms.
3. Network Jitter.
Using the minimum and maximum delay minus the average delay, we get the network jitter ranging from 4 to 6.
Ensure a better quality of VoIP communication, both the positive and negative value of the network jitter is less than 40.