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The Voice over IP paradox

The Voice over IP paradox

Simon Woodside

This work is licensed under a Creative Commons License (Attribution).

Revision History
Revision 2 2003/08/31 sbwoodside
changed the orientation towards availability and the regulation conundrum
Revision 1 2003/08/29 sbwoodside


Voice over IP is paradoxically both internet and telephony at the same time. This article presents the paradox, and associated arguments.

VoIP paradox and explanation

In a nutshell:

Voice over IP is paradoxically both internet and telephony at the same time.

To understand this paradox we must adventure into the wild lands of reliability and availability.


The public internet. Availability on the public internet is best effort which means that other factors (such as price and bandwidth) can be more important than availability.


The public and private branch exchanges of the telephone network. Availability in telephony is counted as five nines. So, 99.999% of the time when you pick up the phone you get a dialtone. That's all but five minutes per year.

So what is this availability beast?


Given a random point in time, how likely it is that the system is working at that moment.

The arbitrary point in time could of course be during an emergency. Will VoIP work during an emergency? Here we run headlong into the paradox! Because the internet is most emphatically not available in an emergency, while telephony must be in order to have a functioning emergency response.

Regulation of VoIP

It is easy to restate the VoIP Paradox in terms of regulation (by the government). (Consider emergency use.)

a. VoIP is telephony and should be regulated.

b. VoIP is internet and should not be regulated.

Both seemingly reasonable statements, given the nature of regulation on telephone systems and the public internet these days.

In the Real World

In the real world there are two types of implementations of VoIP that reflect the paradox. First are the telephony-style implementations where the phones come out and the VoIP goes in. Opposed are the internet-style voice chat systems such as Microsoft NetMeeting, GnomeMeeting, and iChat which are usually supplemental to an existing phone.


There is no conclusion. The situation is playing out in real time.

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