VoIP Call Quality over the internet and what is the best? I tend to see this question a lot in forums and in discussions in general. There seems to be a misconception on what the most important factors are when using the internet for VoIP. Whether you have a SIP trunk connection or remote IP Phones or using a Cloud Hosted Phone solution. Knowing the importance of internet connections before making a investment into VoIP can eliminate a lot of headache.
The majority of people think that because they have uber fast internet connection that they will have no issue with VoIP Call Quality over the internet. Bandwidth is a factor but not the most important. Having a consistent high quality connection is the most important. And when your just surfing or emailing you may not notice the fluctuation in a particular type of connection. Jitter and packet loss are issues that happen and create poor VoIP call quality
Most Common Types of Internet Connections
There are many different types of internet connection such as DSL, Cable, T1, and Fiber to name the most popular. Each one has their unique selling point. For example DSL and Cable are by far the most cost effective. DSL is typically the lowest cost and can give speeds up to 10-15mb up and 1mb down. DSL speeds are determined by how far from the Central Office you are. The closer the better. With Cable Modem the speeds are a lot higher both up and down (around 100mb down and 10mb up). Cable modem is a shared internet connection. Meaning, the backbone cable that feeds the customers is shared amongst all subscribers on that backbone (see image). From the provider to your house or business is normally referred to as “The Last Mile”.
As you can see in the picture of how the cable modem connection is delivered, all subscribers share the feed from the provider. This can generate a “bottleneck” affect and cause slower speeds, jitter and packet loss. This is often seen in Cable Modem connections. Although when surfing the internet you may not realize the bottleneck,. With voice packets you will. What tends to happen is, when the packets leave your office/home router they now enter the shared broadband “last mile”. If that backbone is over subscribed and its load is reached you will experience choppy voice issues or garbled voice. Typically the person on the other end of the call will notice the poor connection. However, on your end of the call it may sound crystal clear. Sharing voice traffic with your data traffic can be a cost effective solution. But, be aware if using a cable modem connection you will experience poor quality sometime I’m sure. Bottle-necking can occur at your router too. If you have a router that supports Class of Service, this can be configured to allow voice traffic priority over data traffic to eliminate the bottleneck.
Fiber and T1
Fiber and T1 connections are dedicated “last mile” connections. You might think that these would then be more expensive and you would be correct. A T1 connection is 1.44mb up and down. Notice the same download and upload speeds? Fiber is the top dog of them all. But again you will pay for what you get.
What is the Preferred Internet Connection?
Clearly the choice would be Fiber. But not all budgets are created equal. If you are going to use DSL or Cable you do run the risk of your VoIP call quality suffering at times. Cable modem does work and works absolutely great. But, there are those rare occurrences when the VoIP Call Quality does sound poor, especially for the person on the other end. With DSL the problem is the low upload speeds. Its not the download that’s the problem, its the upload. Depending on which codec is used for VoIP, with 1mb upload you can have anywhere from around 9-20 calls at the same time. However, that is maxing out your upload. So realistically maybe 3-10 depending on the codec. If you had to choose between cable and DSL I would choose Cable Modem. If you have it in your budget or can afford dual connections of Cable modem and DSL that would be a recommendation too. I would use cable modem for data traffic and DSL for VoIP. The VoIP traffic would go out on the DSL dedicated cable pair for the last mile. For business with a higher budget, I would recommend Cable modem for data traffic and a T1 for Voice traffic. The T1 would allow for a greater call capacity.
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