How Telcos are holding VoIP back
Limitations of the PSTN system
Large standardized infrastructure tends to persist for a long period of time. It's not surprising given the twin factors of expenditure and public habits of a certain way of doing things. But even so, the telephone PSTN system is horribly outdated. For most of us who're used to communicating via email and chat, a fresh look at the phone networks brings this fact home quite forcibly. In this article, we'll look at how the PSTN system is restricted and how it's holding back new technologies like VoIP.
Amongst the many problems with phone these days is the fact that you have to pay heavily for each second you talk to someone. This is because PSTN employs technology called "circuit switching" which creates a dedicated path between the two callers. This is expensive and also wasteful since the line remains idle for long periods of time.
Also, the addressing system is broken. Human's don't remember numbers easily and numbers are no reflection of people. Imagine if you could just type in an email ID - firstname.lastname@example.org and make a call just like with email!
Finally, the analog PSTN line only permits a very poor quality of voice - 8khz is what is standard and this leads to many higher and lower frequencies getting cut off making us unable to differentiate between consonants such as "p" and "b" for example.
Interaction between VoIP and PSTN
In contrast to PSTN, VoIP is very different. The end result is the same, but there's a world of difference in functionality. To start off with, a true VoIP call can be almost free. Because most people have an "all you can eat" Internet service and the bandwidth used up by VoIP is pretty minuscule compared to other forms of media like Youtube, it's essentially as cheap to talk to someone over the Internet as it is to send an email.
Second - because of the flexibility of VoIP, users can negotiate a codec that is of much superior quality than that of the E.164 system. HD voice becomes a real possibility and once users grow used to a better technology, it can be frustrating to go back.
The problem however is that most VoIP users need to communicate with people over PSTN too. This means that the call needs to drop down to the PSTN network and therefore becomes as low quality as a regular phone call. To make matters worse, dialing a number for a VoIP phone makes the call move over the PSTN network in any case! There have been attempts to create a "VoIP directory" so that such IP to IP calls need not traverse the telephone system, and these efforts are still in progress. Hosted VoIP SIP proxy providers are trying to build a network amongst themselves and it's possible that hosted SIP PBX systems will lead the way in creating a true VoIP directory.
And this is the crux of the difficulty between VoIP and PSTN. As long as people insist on using numbers to make calls, we'll be at the mercy of the telcos and never truly break free.