Why Fibre is Best for VoIP

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Alex Sudheim

2 Sep 2022 Clock 6 min

VoIP is becoming an increasingly ubiquitous business tool. Since VoIP is making calls over the internet, the quality of these calls is crucially dependent upon the quality of your internet connection. However, what determines said ‘quality’ is often shrouded in a web of ambiguous technical terminology. The more clarity there is around these concepts the better.

TLDR: With fibre, you pay for speed and stability regardless of how much your data usage fluctuates. With mobile, you pay for data usage while speed and stability can fluctuate. For VoIP calling, speed and stability are of the essence which is why we will always recommend fibre first.

All Roads lead to Home

We connect to the internet predominantly with fixed broadband (DSL, optic fibre cable, wireless internet, satellite) and mobile broadband (3G, LTE/4G, 5G). DSL means ‘digital subscriber line’ and refers to connections over copper phone lines. ADSL, or ‘asymmetric digital subscriber line’, is an individual user of DSL. Given the rapid rate at which copper phone lines are being phased out, DSL and ADSL will soon no longer be part of the conversation. 

Which brings us to the rest of the usual suspects. 3G is the third generation of wireless mobile telecommunications technology, with 4G and 5G the later and greater evolutions. LTE (long-term evolution) is another term for 4G as this generation is theoretically in a continual state of evolution. All of these connections transmit data over the internet using mobile networks via a SIM card. We’re most familiar with this form of connection on our cellphones, although 4G/LTE routers also connect your computer to the internet in the same way hotspotting does when you temporarily transform your phone into a router.

Note: Wireless is not to be confused with wi-fi. The former is when your device connects to the internet without any cables involved; the latter is when you connect to the internet via the short-range signal sent out by a router, be it a DSL, 4G, 5G or fibre router.

Staying connected is crucial in the contemporary workplace

The Fast and the Curious

Service providers use the term ‘bandwidth’ with merry abandon but this can cause confusion. Bandwidth is the theoretical maximum rate of data transfer. One can easily be dazzled by the size of the bandwidth a company advertises. However there is an important caveat to this which is rarely mentioned: the more users, the less bandwidth. A useful analogy is that of a highway. It might advertise a top speed of 180km/h, but if it only has 2 lanes which are crammed with cars, no-one will be going faster than 40km/h even if they’re in a Ferrari. The bandwidth is the top speed, the cars are the users and the actual speed you are travelling at is a far cry from the speed you could potentially be hitting.

When assessing the quality of an internet connection, ‘internet speed’ is often cited as the decisive factor. While internet speed is of course critical to the connection equation, the most important metric in the context of VoIP is not speed but latency

Latency, aka ‘ping’, refers to the amount of time it takes for the signal to bounce back and forth between sender and receiver. Simply put, it’s how long it takes for the request for data to be met by the data provider. We recommend doing the internet speed test at Cloudflare for the most accurate reflection of your connection. The numbers you need to look at in the context of VoIP are ‘Ping’ and ‘Jitter’. Ping measures latency, while Jitter measures how far from the average ping your own is. This is illustrated in the images below.

Figure 1

This speed test was conducted on a wi-fi connection to a fibre router on a 50Mbps line. The ping is a mere 14.8 milliseconds which indicates a stable connection. The result is an extremely low risk of the dropout that makes VoIP calls mangled and choppy, a source of endless exasperation. The jitter is also very low which similarly represents a great degree of stability which results in improved fidelity, quality and stability of calls.

Figure 2

This speed test was conducted on a wi-fi connection to a 4G mobile router whose speed varies between 2 and 12Mbps. One immediately notices a drastic difference. Nevertheless, this is still a perfectly decent connection for most things we use the internet for, including streaming. Of great concern from the perspective of VoIP calling though is the radically increased latency. The ping of 111 milliseconds indicates a relatively long lag between signal sent and signal received, which will more than likely result in signal dropouts which translates to garbled, glitchy VoIP calls. This is a frustration we can all live without. 

Long story short: for VoIP, it’s all about latency and the stability of the internet connection. Some connections, such as satellite internet, are capable of transferring immense amounts of data at jaw-slackening speeds but have a very long latency period. Latency is so important for VoIP calls because these calls are live. Applications such as Netflix are designed to handle high latency by preloading content in order to counter dropout. But because a VoIP call is in-the-moment, this kind of dropout is immediate and is experienced by the user as calls breaking up with words and sentences becoming unintelligibly mangled. 

The superiour latency capabilities of fibre optic cable is why we always recommend this form of connection as optimal for VoIP calling. If you’re making VoIP calls using the Voys app on your mobile (aka ‘softphone’) and are out of range of a fibre router, you will then of course become dependent upon the signal strength of your mobile network. This can flip from rip-roaring LTE to the agonisingly slow 3G, especially if you happen to be on the move.  

Near light-speed pulses in the ether…

Last but not Least

A few other technical considerations are worth bearing in mind. Although you can connect to the router via wi-fi, sometimes plugging an ethernet cable directly from the router to your hardphone / laptop is a good idea. This option is worth entertaining if your machine is too far from the router to ensure a strong, stable connection or there is interference between phone / computer and router, such as a wall with electrical cables running through it.

A further disadvantage of wireless connections is the propensity of the data provider to ‘throttle’ your connection by slowing it down. It’s a bit like loadshedding for the internet – when too many users are straining bandwidth capacity, every user’s connection is slowed to ensure equal internet access for all users. We’re back on that crowded highway in rush hour.

Cutting-edge tech from back in the day

Another surreptitious little gremlin that has an insatiable appetite for bandwidth and connection speed to be mindful of is the background processes running on your laptop. Obviously if you’re busy downloading the entire MCU you’ll strain your bandwidth to breaking point which will render the prospect of a crystal clear VoIP call rather unlikely. However even if you’re doing nothing else on the internet, behind the scenes your machine is constantly updating software which could account for the occasional inexplicable latency issue. 

In short, much in the same way a healthy diet of fibre ensures a smooth, regular digestive system, using fibre to connect to the internet is the best way to ensure smooth, consistent call quality when using VoIP.   

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