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Voice Over IP – an Inflection Point

Voice over IP (VoIP) represents a sharp break from the traditional telephony.

The story of VoIP is important in helping us think beyond the simplistic framing of a “digital transition”. The first stage of any technology is emulating the old. Indeed, digital telephony was just like traditional analog telephony—just FBC (Faster, Better Cheaper) but not fundamentally different. Merely changing from analog to digital isn’t transformational in itself. But it creates the opportunity for transformation. VoIP is a break with the past and an entirely new approach to the concept of a phone call.

Telecom and VoIP

Today’s telecommunications and Internet governance policies are premised on the assumption that telecommunications services are network services, with each layer built on a more basic layer starting with the physical layer and applications riding above this.

The Internet is built upon a very different principle that turns this layering paradigm on its head. Applications are not dependent upon layers as such but rather take advantage of opportunities. Rather than relying on a network to preserve the content of the message, we convert the speech to packets that can travel independently. Each can find its own way towards a destination. It is only at this endpoint that they are recovered and interpreted as speech.

With a telecommunications service, one size fits all. Resources are set aside to assure a clear path, and if the resources are exhausted, the circuits are busy, AKA, we have 100% failure.

With the Internet approach, we can take advantage of extra capacity if available and even add video. If there is limited capacity, we can choose alternatives such as text. It is our choice, not the providers’. The advantage goes to innovators rather than the highest bidder.

On the surface, this sounds very risky, yet we now take video for granted—something we couldn’t do in the half-century of picturephone on the traditional phone system.

The Public Packet Infrastructure

In this previous article, I proposed a packet infrastructure that would serve as a common platform for all connectivity. By pooling all connectivity into a common infrastructure, we can unleash the abundance that the Internet hints at and eliminate the artificial barriers that create a digital divide device and limit innovation.

Heretofore we’ve needed a separate phone network to meet the exacting demands of phone calls. Voice over IP (VoIP) enables us to achieve these goals without having a separate phone network, and we can do so at no cost above the shared cost of the common infrastructure. That cost is far lower than the cost of a telecommunications infrastructure because it is far simpler and benefits from sharing facilities. It also aligns incentives because we can own our local infrastructure since we are no longer dependent upon a provider to assure phone calls work.

VoIP works on very different principles from traditional phones calls. Understanding that difference enables us to formulate policies appropriate to the age of the Internet rather than the century-old policies that dominate telecommunications policy.

Traditional Phone calls

One of the themes in my writing is that transformative ideas are the result of discovery rather than the result of improving an existing technology. By the 1990s, the phone network was digital.

A traditional telephone is simply a microphone at one end and a speaker at the other. The task of a service provider is to preserve the sound (a waveform) over any distance so that the sound coming out of the speaker at the other end sounds just like it did at the microphone. The breakthrough came in the 1930s with the invention of digital telephony.

The advantage of a digital system is that there are just ones and zeros. So if the signal drifts a tad, it can be restored because there are only two possibilities. This ability to regenerate the signal over any distance is the key to assuring high-fidelity calls.

It’s the providers’ responsibility to assure that each sample arrives at precisely the right time because our hearing is very sensitive to the slightest glitch. Some sounds don’t exist on their own but rather emerge from the timing of the speech, as with the “l” in shalt. Slight changes in timing can also change the meaning.

Discovering VoIP

As with any innovation, there are multiple origin stories. Alon Cohen of VocalTec tells how he came up with a simple algorithm for doing voice on their internet packet network by doing simple buffering. This allowed the timing of the voice signal to be preserved by inserting a very small initial delay. He was surprised to find his customers using his software across the public Internet.

It worked because, by that time, the capacity of the Internet had increased to meet the demand for web capacity. This is an example in which the growth of generic capacity enabled innovations like VoIP.

The technology of VoIP came to the fore when Skype enabled people to call their relatives on other continents for free by using their existing Internet connection. As a bonus, they could use also use video for free. For a small cost, the calls could also connect out to traditional phones.

The appeal of a dramatically lower cost for phone calls was the selling point for Skype. But that would be like treating a personal computer as just a nice typewriter (for those who remember typewriters).

How VoIP works

Animated GIF showing that packets are not waveforms

The basic idea of VoIP is simple. As with traditional digital telephone, we sample the waveform, but instead of relying on the network to preserve the order and the timing, we tag each packet with a timestamp and destination and send it off on its way. Each packet can take a different route.

The destination device isn’t just a speaker—it’s a powerful computer that can accept the packets in any order and put them back in sequence. A small amount of buffering provides ample time to perform this magic.

That intelligence also enables the software to fill in the gaps, so instead of a click, the gaps would be filled by guessing what was missing.

What is remarkable is that once the voice has been converted to packets, those packets are autonomous. With sampling, you could watch the waveform on the wire and listen in. The VoIP packets have no relationship to the other packets in the conversations. This is counter-intuitive because it means that you can’t look at the wire and see a snippet of a conversation, and you can’t make promises about the quality of a phone call!

The surprise is that avoiding dependency upon a provider has freed us to innovate. We can offer better audio when available and even do video at no additional cost by eschewing guarantees!

To put it another way—policies that manage scarcity turn out to perpetuate scarcity. We need to enable abundance.

VoIP and the Virtuous Cycle

In practice, the software is far more sophisticated and can take advantage of intelligence at both ends to coordinate and adapt to the actual capacity of the network. This enables VoIP to be used on lines that aren’t good enough for traditional phone calls while also being able to take advantage of additional capacity to offer very high-fidelity voice.

Phone companies were never able to make a business case for Picture Phone® because it was treated as a very expensive phone call.

The key is that VoIP takes advantage of the opportunities for innovating afforded by generic packet connectivity. At first, there wasn’t enough capacity for VoIP. That was OK because there was already a purpose-built, albeit a very expensive, phone system.

The Internet architecture decouples the application from the packet transport. There is no way to pay an Internet provider for priority. The packets are autonomous, and there is no provenance (relationship with user) inside the network.

This permitted the virtuous cycle of innovation to play out. Each new use for generic connectivity created a demand for more generic capacity, which enabled more applications. The capacity created for the web was a major driver. Today we take it for granted that we can work from home using high-quality video conferencing.

The same dynamic has also enabled the emergence of video streaming. Here one factor is caching—the ability to stage content near the user. There isn’t just one way to take advantage of generic connectivity—this is why I use the term “opportunity”. It doesn’t prejudge any particular use case.

Hiding in Plain Sight

Thanks to the intelligence in our devices, VoIP can interoperate with the existing phone networks using SIP (Session Initiation Protocol). You can place calls to and from the existing phone network and assign phone numbers to SIP lines. My own “landline” is just a Google Voice number using an ATA (Analog Telephone Adapter).

This allows people, especially policymakers, to treat VoIP calls just like traditional phone calls and even to attempt to apply legacy policies. Protecting old policies also led to the demise of the ENUM top-level domain because it threatened the very fragile architecture of the phone network and the accidental dependencies on their numbering plan.

In 2008 I attended a conference (eComm), and one speaker commented that the new LTE network was not suitable for voice—just data. Today we’re scrapping the 3G voice network because the techniques used for VoIP have made the LTE network a better voice network than the purpose-built 3G voice network. The same technique I used myself when I used a VoIP application over my smartphone’s data path!

The entire phone network is not just an emulate over the Internet. ATT used to have 50 story windowless buildings to house all the switching gear. Now that phone calls are apps. There is no switching! That entire 50 story building is now just an empty space filled with servers or other gear. Perhaps offices but most people like windows.

The hollowing out of the ATT building and the rest of the phone network has larger implications. We’re still building expensive infrastructure based on the givens of traditional telephony, such as the idea that we need to share distant cell towers and then have that traffic “backhauled”.

Why VoIP is so Important

Now that we know we no longer need a separate, dedicated phone network, we have to look at public policy from first principles. How do we provide a common infrastructure? The virtuous cycle that has enabled VoIP and streaming services threatens the existing telecommunications business model. We need a policy that builds on the virtual cycle and works to create more opportunity and capacity.

We now know that we can share a common infrastructure for even the most demanding applications. Our policy can focus on enabling a Public Packet Infrastructure. Just as software has allowed VoIP to interoperate with the existing telecommunications network, the PPI can coexist with the existing telecommunications policy, thus allowing a smooth transition.

Communities investing in this common infrastructure will drive the virtuous cycle as we create new applications and services while saving families thousands of dollars on telecommunications services.

By Bob Frankston, IEEE Fellow

Bob Frankston is best known for writing VisiCalc, the first electronic spreadsheet. While at Microsoft, he was instrumental in enabling home networking. Today, he is addressing the issues associated with coming to terms with a world being transformed by software.

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