Ever since the early days of VoIP, there have been perceptions about the voice quality. Indeed, such perceptions were justified when the Internet was still relatively new and lots of people were still on dial up. In today's world however, dial up is an anachronism and broadband penetration is extremely high thereby giving VoIP the perfect opportunity to flourish. As always, initial adoption of such technologies takes place in businesses which then trickles down to the public. In this article, we look at how we measure the quality of voice service with VoIP.
The Mean Opinion Score
One of the most prevalent techniques for measuring VoIP quality is a subjective score known as the Mean Opinion Score. Most of us will be familiar with the little rating quiz that pops up after Skype calls asking you to rate the experience on a scale of 1 to 5, which 5 being the best if it's just like face to face conversation.
Most people rate the PSTN system as between 4 and 4.5 and this really highlights how much people have gotten used to poor service and think it's good. How many of us can remember spelling out our names tortuously trying to make the listener differentiate between a "p" and a "b" for example? And yet when asked to provide feedback on the experience we call it OK!
In VoIP these days, you can get far better voice quality than on a PSTN phone including HD voice capabilities which incorporate higher harmonics to give a clearer sound. In any case, as of now VoIP providers are happy if their services are rated the same as a normal telephone call.
Network Issues and QoS
But VoIP quality doesn't have to be merely subjective.
There are several technical indicators which provide a very good idea of the quality of voice service. For example, factors such as jitter and latency can easily be measured systematically. In fact, routers can be instructed to not let such parameters go beyond certain values for voice data thereby ensuring a proper voice experience at all times. It's usually necessary to set up a Virtual LAN or VLAN for this purpose.
Of course, we can't use these technical factors to compare VoIP quality with the PSTN service since we can't use the same parameters on the latter due to its analogue nature.
One thing is for sure though. As more and more people adopt VoIP, there will be more calls placed solely over the Internet without needing the PSTN lines and then we will see the true difference between the two systems.