Surveillance or Security?: The Risks Posed by New Wiretapping Technologies by Susan Landau Read Free Book Online Page B

Massachusetts.55 At the time, the entire cross-capacity of the ARPANET was
only two or three 56-kilobit lines, the equivalent of two or three dial-up
modems. A voice call, which is very rich in data, could use up the entire
capacity. Thus the issue was how to compress the data rate for voice calls
way down. While current voice calls use about 64 kilobits for a call, the
1970s effort did the call using just 2 to 3 kilobits.56 "Remember, the phone
companies were looking over our shoulders laughing," Cohen recalled
years later, "and our job was just to prove it could be done. We did. 1117
    The network did not have reasonable bandwidth for voice calls until the
mid-1990s. Speed was part of the problem. While emails can take a few
seconds to transit their route and that presents no difficulty, people will
drop a phone conversation if there is as much as a half second delay in
transmission. Early versions of the network were too slow to support realtime voice compression that, in the 1970s, took two or three cabinets of
cutting-edge electronics to achieve. Today's Internet is much faster than the
ARPANET of three decades ago, and such compression is no longer needed.
Voice communications over the Internet, known as VoIP, has arrived.
    VoIP means that the voice conversation is routed over a network using
the Internet Protocol. This network could be the Internet itself or it could
be a smaller regional or local network. Though the communication is a
real-time voice communication like a phone call, the technology is not
like the PSTN. Unlike the dedicated circuit that is established for a telephone call, at some point during the call, a VoIP communication is converted into packets that are sent over an IP-based network and then
reassembled at the endpoint.
    The simplest form of VoIP-and the first to come onto the market-was
transparent to the user. The caller uses a telephone to make the call which
then travels, as it would normally, to the telephone company's central
office. There the call is converted to a digital signal, sent over an IP-based network to its destination; at the final hop to the recipient, it may change
to an analog signal (whether it does so depends on the type of phone and
network being used). This is the model that Vonage employed.

    Of course, there is no reason that the customer's telephone has to be
an old-style voice phone; it could be a more modern IP-based telephone.
To the user the device itself looks-and acts-like a telephone, but its
innards and actions, as well as the connection to the outside world, are
quite different. The telephone converts the signal from analog to digital
and connects to a data network rather than the telephone network.
    There is also a VoIP model that fully dispenses with the telephone; one
uses a computer to make the call and the Internet is used for routing the
communication (to another computer). This is how Skype58 works, but
Skype goes one step further. Skype is a fully peer-to-peer based VoIP system:
any machine running Skype may be used in the transmission of another
Skype user's call.59 Skype is a realization of Baran's peer-to-peer model of
communication. Just as the telephone company executives observed, this
communication system turns the telephone network model upside downleaving the utility to provide only the underlying wires.
    The difference in networks means that the "phone" is not quite a telephone; this causes important differences. The telephone network is powered
by electricity but because PSTN telephones are powered from the central
office, the telephone network tends to stay up even when the electric
power grid goes down. Another issue is that IP-based telephones can run
into quality-of-service problems: if the network is being heavily used, communication quality can suffer. On the PSTN the situation is handled differently: either the call goes through and there is a steady connection or
one hears: "All circuits are