If you are using a VoIP phone system, there is a good chance you have experienced poor call quality. This article discusses the causes of VoIP call quality problems and what you can do to correct them.
The causes of poor quality VoIP calls are easy to diagnose and correct. Your VoIP Service Provider should be able to identify and work with you to correct these problems. More importantly, these problems should not be ongoing. If your VoIP Service Provider is unable to correct your call quality problems, you need to find a different provider.
1. The Problem: Jitter
Jitter is a common problem of the connectionless networks or packet switched networks. Because the information (voice packets) is divided into packets, each packet can travel by a different path from the sender to the receiver. When packets arrive at their intended destination in a different order then they were originally sent, the result is a call with poor or scrambled audio.
Jitter is technically the measure of the variability over time of the latency across a network. Jitter is one of the most common VoIP call quality problems.
The Solution: Use Jitter Buffers
A jitter buffer temporarily stores arriving packets in order to minimize delay variations. If packets arrive too late then they are discarded.
2. The Problem: Latency
VoIP delay or latency is characterized as the amount of time it takes for speech to exit the speaker’s mouth and reach the listener’s ear. Latency sounds like an echo.
There are 3 types of delay commonly found in today’s VoIP networks;
- Propagation Delay: Light travels through a vacuum at a speed of 186,000 miles per second, and electrons travel through copper or fiber at approximately 125, 000 miles per second. A fiber network stretching halfway around the world (13,000 miles) induces a one-way delay of about 70 milliseconds (70 ms). Although this delay is almost imperceptible to the human ear, propagation delays in conjunction with handling delays can cause noticeable speech degradation.
- Handling Delay: Devices that forward the frame through the network cause handling delay. Handling delays can impact traditional phone networks, but these delays are a larger issue in packetized environments.
- Queuing Delay: When packets are held in a queue because of congestion on an outbound interface, the result is queuing delay. Queuing delay occurs when more packets are sent out than the interface can handle at a given interval.
The Solution: Prioritize
Prioritizing VoIP traffic over the network yields latency and jitter improvements. Policy based network management, bandwidth reservation, Type of Service, Class of Service, and Multi-Protocol Label Switching (MPLS) are all widely used techniques for prioritizing VoIP traffic. A quality VoIP router can solve many of these issues and will result in business quality VoIP service.
3. The Problem: Poor Internet Connection
Most ISP’s are designed for web surfing and not VoIP. Transporting voice packets is different and requires an additional set of internet protocols that your ISP may not be providing.
The Solution: Business Class High Speed
Fortunately, most of the ISP’s, including cable and DSL high speed internet providers offer business class high speed internet service that is acceptable.
4. The Problem: Inadequate Router
Bad equipment is bad equipment.
The Solution: Install a Specialized VoIP Router
This is one of the most common causes of call quality issues. Many small businesses use their internet connection for both voice and data. This is perfectly fine as long as your router has the ability to prioritize VoIP traffic.
Without a router that is configured for packet prioritization, call quality can be impacted by the other users on your network. For example, if during a call, another user on your network downloads a large file, without packet prioritization, your call quality could be degraded. A VoIP router prevents this from happening by giving priority to voice traffic on your network.
VoIP routers are not an expensive piece of hardware. A VoIP router for a small business ranges from $300.00 for a five person office to under $1,000.00 for a 25-person office.
5. The Problem: Internal Network Improperly Configured
VoIP is less than 10-years old. Many companies do not consider the higher quality demands of VoIP communications. If your company decides to route both voice and data over the same network with out properly configuring your network for VoIP traffic, you can expect to have call quality issues.
The Solution: Network Configuration
This is one of the easiest and least expensive problems to correct. A VoIP capable router that is properly configured will generally solve the problem.