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Troubleshooting Packet Delay in VoIP

Posted by Natalie DeCario on August 28, 2013 at 6:32 AM
Natalie DeCario

Matt Larson works with VoIP Spear, a VoIP Quality Monitoring and Testing Company based in Canada. He is currently based in the South East Asia, where he gets to support his scuba diving with writing for the VoIP industry. He is immensely thankful to VoIP for making this lifestyle a possibility.

Delays have been problems in communications since Alexander Graham Bell invented the telephone. Back when it was just traditional telephony, the system experienced variable delays, usually caused by low quality satellite connections. Now, in digital communications, delays pertain to delays in the travel of packets through the network. These packet delays cause increased latency – defined as the amount of time it takes a packet to reach its destination – which can then lead to more perceptable VoIP problems, such as feedback, echo, stalling, and low video and audio quality.

Troubleshooting Packet Delay in VoIPPacket delays are actually normal ocurrences. In a healthy network, any effect on VoIP communications is negligable. Increased latency is imperceptible, at best. The case is different in systems with chronic packet delay problems. VoIP becomes a second rate telecommunications choice, despite the leaps it has taken in the past two decades.

This need not be the case. There are different kinds of packet delays and, once the user or administrator determines their kind of delay and if they have access to fixing it, they can try to troubleshoot packet delay issues. At the very least, this gives them a temporary solution.

Types of Packet Delays

Packet delay is normal because data packets naturally go through a system of routers, switches and other hardware. It also goes through wireline phone systems at some point during transmission and reception. That's how voice and video are relayed from the different communications endpoints.

The amount of delay becomes abnormal because of compounding circumstances.

There might be network traffic or congestion during transmission. Or, your network connection is slow and may be unsuitable for VoIP. This results in IP Network packet delays, which is defined as delays caused by slow and/ or congested network connections. These delays can be somewhere between ten milliseconds to more than a thousand milliseconds.

Another type of delay is the End System Delay, which is the collective term for delays during data handling. At this point, the voice data necessarily goes through encoding, jitter buffer and decoding. Within these steps, delay occurs. Encoding can incur up to 30 milliseconds of delay. Decoding delay is less than this. What adds to the end system delay is the delay caused by jitter buffer. The buffer removes variations in voice quality. Say, there is a long IP Network Delay. The jitter buffer size will naturally increase because of this, causing delays of up to hundreds of milliseconds.

User Experience with Packet Delay

The user experience is, of course, affected in varying degrees when there is packet delay. Problems include echo and feedback, among others. There is a perceptible reduction in voice and video quality.

In a scenario where there is delay, the effect may not be obvious during one-sided conversation. The jitter buffer works to bridge the gaps in voice data when only one side is sending out data and the other side is only receiving it. This is not the case in a normal multi-way conversations where all sides are receiving and sending out data packets. Disruption in conversation can be in the form of doubletalk, echo and speech pauses.

Troubleshooting Latency Problems Caused by Packet Delay

For network administrators and managers, troubleshooting any latency and packet delay problem starts with monitoring their networks and systems. You can use services like VoIP Spear for this. Through these third party services, your networks' endpoints are monitored and tested at select intervals for factors that affect VoIP quality, including latency, packet loss and jitter. This is a way to get to the true source of the problem and address it accordingly.

To a certain degree, end users can also troubleshoot latency problems caused by packet delay.

  1. One of the first things to do is determine the cause of your VoIP problems. You can also use VoIP Spear's services for this – the company offers free accounts for single endpoint testing. Once you've determined that variations in your VoIP quality is caused by latency issues, you can apply fixes from your end.
  2. Voice and video data travel through different systems before you get to hear and see it. You can alleviate perceptible delays by reducing the systems that data need to go through. If you are accessing VoIP via wi-fi, cut down the wi-fi and plug in directly to your router or switch.
  3. Cable and adapter damage also affects how voice and video data are transmitted and received. Check and replace any damaged hardware.
  4. Sometimes, all it takes to improve network connection is a power cycle. Turn your router off for about 20 seconds and then turn it back on.
  5. Shut down other applications that use bandwidth.
  6. If you have a new router, you can update your QoS settings and assign the highest priority to voice.

Tags: VoIP

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