In my neighbourhood power lines are above ground and the local cable operator shares many of the same poles with the utility and phone company. Every so often if you look up you see a rather ordinary, boxy-looking 120/208V transformer. By ordinary I mean it is not one -- or three -- of those robust "cans" that the utility uses for distribution to homes and businesses. If you have a set-up like this in your area, follow the output from the smaller transformers to see where they go. Invariably the power leads to the cable company's equipment.

Now think about this. In order of reliability, which service provides the most up-time? Will it be cable? No. How could it be? If you blend the inevitable equipment and network faults inherent in the base cable system with the line outages that occur on the AC utility system you will not get a more reliable system. As long as cable requries AC power at multiple interconnect points beyond its facilities it will be saddled with system reliability that is no better than the utility grid and is usually worse. What about PSTN (or POTS)? Analog 2 wire phone lines are DC powered from the local office. Sure the DC is derived from AC powered rectifiers but every CO is backed up by a bunch of batteries and often an alternate source (ie: a generator). Ditto for the wireless telephone networks. Cable guys may have generators and UPS's in their offices but they can not cover every single point of AC access on their system with an alternate source.

On August 14, 2003 everyone around here who had cable internet access lost their service. So if they had VoIP via cable they would have lost that. I have DSL service on my telephone line. I did not lose basic phone service and, initially at least, I did not lose my broadband connection. You may wonder how that can be since my DSL connection relies on an AC powered router. I have a UPS. When the battery died the DSL went down at my end. The point is the service was still available for anyone who had the means to power their own equipment. That was not the case for cable users. Even if you had a 300 KW UPS with 8 hours of battery and a Caterpillar diesel gennie with 6 days of fuel, there would have been no raising of the cable connection until the local grid was fully powered by the utility.

This inherent weakness exists throughout the cable distribution system. It is a significant competitive disadvantage that has been exploited recently by a local phone company (Bell Canada) in advertising that has trumpeted the reliablity of the POTS network. I think these ads have been right on and the marketing message is unmistakeable. Even if download speeds are faster on your cable internet link, even if you can buy a set-top box and download on-demand movies, even if the cable guy wants to provide voice services; think about reliablity. The monolithic phone companies are starting to realize that they are in the vanguard of something "new" -- always-on technology that has existed for over a century. What a concept.

Framing the marketplace in this way makes it clear that talking up VoIP technology is irrelevant as a sales pitch strategy if you are dealing with power users or business customers. The only thing that matters are services. I like the "follow-me" service with e-mail and SMS messaging capabilities that I'm getting from my phone company now. It's not a VoIP technology but it could be; as a user I don't really care. It's a neat service that I like using.

VoIP is still a classic disruptive technology in the mode described by Christensen, but only if you run a telephone company that has not invested in broadband technologies for your customers. VoIP is a sustaining technology on a DSL broadband network running on POTS lines. A services revolution has started in telecomm; enabled by, but not dependent on, consumer VoIP availability.