Packet loss - packets contain the information of the conversation. If IP packets are lost, information is lost and conversations will break up. Jitter, or packet arrival time variation - latency may average 300 milliseconds or less, but if it varies widely, as it does often on the public Internet, conversations will sound uneven and may even be unintelligible. These parameters are fundamental to the quality of such real-time data as voice, and fortunately, there are good ways to deal with them. A key indicator of how the network is likely to perform is capacity utilization during peak traffic times.
Congestion increases during peak times and congestion contributes most to call quality problems.
Even the best IP network does not operate properly all of the time. Also, this kind of redundancy is essential to ensure quality of service in other respects. Employ network management tools to monitor and manage the performance of the network at all times. Without these tools, VoIP providers cannot possibly spot problems and provide real time corrections, either on an immediate or longer-term basis. Conclusion All voice traffic will one day travel along with other forms of data on IP networks.