VoIP and Quality of Service (QoS)

We were approached to investigate poor performance on a recently installed Hosted internet telephony solution, though much of what follows also applies to a lesser extent with OnPrem

The main issue was poor voice quality, (noise), and latency, (delayed and, or, broken speech), at certain times of the day, usually first thing in the morning and just after lunch.

The reason for the issue at these times was users logging into their computers and immediately using the internet at the same time.  Other factors like video streaming, antivirus updates, downloading large files, remote workers logging in and so on also affect voice quality at other times of the day to a lesser extent.

The issue was immediately obvious, they were using fibre broadband for both voice and data without consideration to QoS, e.g. ensuring that voice traffic from the internet always had sufficient bandwidth to give good voice quality.

QoS can be achieved in a number of ways, including – 
Converged Broadband – the simplest solution that uses voice and data on the same broadband but guarantees bandwidth, and thereby QoS, to the voice network, obviously at the expense of the data network.
Assured Broadband – our recommendation for all but the smallest installations is to use a separate broadband, and guarantees QoS therefore, that only allows voice traffic to pass through it.
VLAN– this is where it all gets technical.  Simplistically a VLAN can be used to separate internet bandwidth into voice and data in the same way as Converged Broadband but is done internally on the local network.  This requires network devices like switches and firewalls that support VLANs.
Leased Line
All of the above solutions have one problem in common, they all use a contended broadband that is shared with other subscribers from the local exchange, for business subscribers the contention ratio is 20:1, for domestic it’s 50:1.

The only way to avoid contention issues is to have a dedicated, leased, internet line.  Leased lines have a contention ration of 1:1 and are typically available up to 100Mb.  This isn’t an article about leased lines but clearly QoS becomes much less of an issue, but can be expensive.

What did we recommend for this client?
Our recommendation would be an Assured Broadband, ideally with the provider of the telephony service.  Other factors may come in to play such as scale, broadband speed, Hosted telephony, (OnPrem uses less bandwidth), and the additional cost of another broadband.

If you’re experiencing similar problems with your telephony please give us a call.

Leave a Reply

Your email address will not be published. Required fields are marked *

Privacy Policy

This website uses cookies to ensure you get the best experience on our website.

Happy to Accept?