The Reason Your VoIP Service Sucks (Why is my VoIP not delivering?)

19th July 2018 by jude

At the heart of a great VoIP service is a good connection to the Internet. But what does a good internet connection look like? Is it a download speed? An upload speed? A connection ratio at the DSLAM?

In saying “connection to the Internet” we aren’t just referring to your internal network, router and switches etc. but also the folk who route your calls globally, the Tier One Telephone providers. Most of which will be using VoIP themselves. So where to start?

Well it’s simple, it all comes down to stability

Whilst there are many factors to a good internet connection, at the core is stability. A lot of internet traffic uses the TCP/IP Protocol, which was invented in the 1970’s. In those days internet speeds were a fraction of what they are today and fairly unreliable. One really useful feature of this protocol was if a packet (piece of data) happened to get lost, the software would be aware and request it to be resent.

Whilst this works for most internet uses, including video and music streaming (through buffering), it’s useless for voice. Shouting HELLO over and over again doesn’t quite work, does it? Voice demands a more stable connection than any other application.

At byphone we use a measure called Jitter to assess the stability of a connection. This is the variability over time of packet latency (delay) in a network. No latency will generate a score of zero. A high quality network will have a score of under 4ms. If the Jitter score is high (above 10ms) then it’s likely that voice data will arrive after it’s useful. The moment will have passed and it will get dropped from the call.

A quick measure of Jitter will tell you whether an internet connection has potential to carry voice. However stability implies a period of time. Jitter tests should be therefore be conducted over a period of time, to build a more accurate picture of the overall connection stability.

So, what are the factors that affect your networks Stability?

One: How good is your standard broadband?

Many people will tell you that their internet connection will get download speeds of 10mbps and up, (theoretically enough to carry 50 voice calls), so it should be fine, right? Well… there are several factors that can affect this.

ADSL (the standard in broadband) works using electrical signalling. Electricity can be unstable and can vary with power surges or contact with substances like metal, magnets etc. The longer the connection has to run to an exchange point, the greater the potential for interference. This means proximity to your connection is key when using this type of broadband, as a connection a mile away from an exchange (electrical signal) will be more stable than one which is 5 miles away.

Two: Is Fibre really better?

The simple answer is yes. As this technology uses optical light pulses there is no degradation in signal when connecting to the local exchange – as a result it’s much more stable. Your connection will be as strong at five miles away as it is as at one mile away.


Three: Bonded Pair, are we stronger together?

Ethernet-based multi-pair bonding technology are connections made for businesses and carry performance assurances that can provide stability. However, they are expensive and have limited capacity. It can therefore be hard to justify the additional expense given the more restricted capacity. These types of connections are best when using a leased line or fiber is not available.

Four: Leased Lines, is it worth the price tag?

These lines are a business grade product that guarantee enhanced performance and provide the most stable connection. This improved performance is a little more costly, but the expense can be shared with data connection and used to improve your overall stability.

If you choose this route it’s important to partition part of the line specifically for voice to protect against data swamping (more on that later). The line needs to be partitioned at installation, to avoid being hit with substantial additional costs when routers are later required to partition the line.  

Five: Contention, is it an issue?

This really only affects those connections with limited capacity. Essentially, if the local exchange is busy then the connection will get shared with all the other users and can have a noticeable effect on stability when the connection is weak to begin with.

Six: Data swamping – Does capacity improve stability?


Internet protocols try to download files as quickly as the connection or equipment will allow. So if you are file sharing or streaming from youtube the connection may become saturated or fully utilised. Sometimes the Internet providers will throttle the connection a little, particularly during video sharing where they may limit the speeds to a 1 mbps or thereabouts. This is however set by the local exchange.

Take Fibre for instance – with a shared Fibre connection (data & voice) the aim is that the capacity or throughput of the connection doesn’t fill up. However, with this we are relying on the ISP to throttle the download speeds a bit and quality of service (QOS) settings on the router to throttle the upload speeds.

Even with this, voice can get swamped by data on the network itself. As the protocol instructs packets to fill all available bandwidth the swamping can occur at switch or router levels before the data can be managed.

So technically, a shared, fast data connection with reasonable quality routers should be enough to avoid data swamping. However, this isn’t always the case. Sometimes the call quality suffers. This is why it’s recommended to keep the voice and data separate on the network and separate connections to the internet.

Using seperate connections therefore makes it impossible for data to swamp the voice as they use separate networks and connections to the Internet.

Seven: Is your internal equipment up to the job?

Switches need to have enough processing power to handle the voice traffic in a timely manner. Older switches combined with high traffic can lead to stability issues.

Routers depend on the speed of their processors. To handle large amounts of data they need modern processors. Routers can also manage outbound traffic with quality of service (QOS) settings. This prioritises the outbound voice traffic going through that router.  

Cabling that is older than ten years may have degraded to the point that it affects stability. In some cases our engineers have seen cabling secured by metal stables which impairs the stability of the electrical signals.

What’s the best course of action?

A good connection needs stability above all else, with the capacity to serve as a buffer for other variables that can affect performance.

A strong recommendation is to separate the voice and data networks with separate connections to the internet. By combining the connection you are relying on a much more comprehensive management system and hoping that the ISP throttles some inbound services.

That’s why at byphone, we developed the Voxbox series of tests, to assess the suitability of a network and a connection for voice connections.

Find out if your internet connection can support voice.

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